Tiberius is born in April 1862 to Tybalt and Igraine Lestrange. He is the only child for four years before the arrival of his sister in 1866 causes his mother to die. A quiet and contemplative child, Tiberius does not display any overt sign of magic until age eight, when he turns his sister purple. He doesn't really remember the circumstances surrounding it, but as far as first acts of magic go he thought, even at the time, that it was rather silly.

Tatiana has a much more impressive display of magic in 1872 when she lights a stray dog on fire. Tiberius is a little jealous that he can't figure out how to light animals on fire with his mind. Honestly, he is a bit put out that he doesn't have more magical outbursts in general, but there's not much he can do about it. He spends most of his later childhood following his father around and trying to learn magic by watching the older man (or really by osmosis, since his father is hardly interested in teaching him anything). He attempts to read some of his father's books, but has difficulty putting them into any practical context when he isn't able to use a wand. Hogwarts simply can't come soon enough.

As he has already been noted to take after his father in almost every way, it is surprising to absolutely no one when Tiberius is promptly sorted into Slytherin. His experiences as a first year at Hogwarts are the first indications that he has that he can't really relate to other people, though he at first doesn't recognize this as a fault in him but rather thinks all of his classmates are obnoxiously talkative and energetic. He studies diligently and, since he is almost entirely antisocial, masters the rudimentary lessons very quickly. Feeling that he is wasting time by just plodding along at the same speed as his classmates, he starts researching topics of interest to him in his free time and is more or less always found in the library.

The fact that he is at Hogwarts in March of 1875 when his father makes headlines means that there is no way anyone in the family can shield him from the news; not that he takes it particularly hard. In fact, the lack of emotional reaction to hearing that his father is a mass murderer and will be sent to Azkaban indefinitely rather alarms his aunts and uncles to whom he is remanded at the end of his second year.

Tatiana is more or less adopted by their aunt Mariana Macnair, but the woman doesn't care for sullen and strange Tiberius, who is shuffled off to Lucius Lestrange's home in the country instead. He supposes he misses his sister, but this attempt at emotion is quickly replaced by enthusiasm when he discovers that his uncle Lucius has a personal library to rival his father's, which means his personal studies will not need to be interrupted.

While 'home' for Christmas of 1875, in the middle of his third year, Lucius catches him sneaking in to the library to read. Rather than reprimand him, his uncle directs his studies to more "age appropriate" material, and as a consequence of Lucius' tutelage Tiberius begins to learn even more quickly. He is constantly frustrated by the limitations of the unrestricted sections of the Hogwarts library, and uses his new living situation to attempt to befriend his older cousin, Claudius, just enough that he can occasionally beg a book from the restricted section. Less useful are his younger cousins Valeria, who began school in 1876, and Cassius, who joined them the following year. Also in third year, he adds Ancient Runes and Arithmancy to his core classes.

In 1877, his uncle purchases a house in the budding town of Hogsmeade, and Tiberius moves along with his cousins, which also brings him closer to Tatiana as the Macnairs have also opted to move. That school year, his sister joins him in Slytherin as well, completing their reunion as much as possible whilst they are still entrusted to separate guardians.

During his fifth year (1877-1878) Tiberius is named prefect. Of much greater import (to him, anyway), he stumbles upon some rudimentary fundamentals of occlumency and legilimency whilst studying for his OWLs, and is fascinated with the subjects. He confides his interest to Lucius, who encourages his interest and agrees to help with practical lessons come summer.

Tiberius drops Arithmancy, Astronomy, Herbology, and History of Magic, but adds Alchemy to his class load for a total of six NEWT level classes. He also spends as much time as possible with occlumency and legilimency. The former comes very easily to him, as he's never been emotionally expressive anyway, but the latter is decidedly harder, especially without the benefit of practice lessons during the school year. One breakthrough occurs when he locks eyes with a female classmate and realizes that she's carrying a torch for him, which is rather baffling. Intrigued, Tiberius indulges her interest. He takes her virginity (and loses his own) at the end of their sixth year.

Simultaneously, he begins to take a keener notice of his younger cousin, Valeria—some would say that his interest in her borders on the obsessive, though he tries to hide this from everyone and is mostly successful.

During his seventh year Tiberius briefly continues his liaison with his female classmate, until she breaks things off due to his somewhat aggressive tendencies during intimacy. He isn't too heartbroken about it. Instead, he turns his attention to his cousin, Valeria, who seems to notice his interest and increasingly to return it. After a lot of sexual tension the two eventually kiss, though Tiberius is hesitant to go further for fear that Lucius might find out and see him skinned.

Following graduation Tiberius doesn't really want to do much of anything, and for a while he doesn't. He continues independently studying the Dark Arts and experimenting with the Unforgiveable Curses, which leads him to commit his first murder in October of 1882 (by proxy, via a combination of the Imperius Curse and legilimency that he finds rather thrilling). He travels when the fancy strikes him, having come into the inheritance that his father left him, and occasionally conducts 'experiments' on his younger cousin Cassius when the boy is not at school. This leads him to become rather more well-acquainted with Cassius' personal life than he would like to be.

Following accusations that has no direction in life and no desire to do anything, Tiberius arranges a betrothal for himself. His bride-to-be is only fourteen at the time, which gives him a comfortable space before they wed.

In early 1883, Tiberius decides to do Cassius a favor by making a boy in his year who Cassius has an inappropriate attachment to 'disappear.' The solution isn’t as foolproof as he had imagined, but he doesn't discover that until much later.

Valeria marries in 1884, and far from being disappointed by the match Tiberius is rather ambivalent; this means he can start screwing her more or less without consequence. The first child she bears, late in that same year, is his, and they are both very much aware of it.

Beginning to feel a bit restless doing (in the eyes of polite society, anyway) nothing with his life, Tiberius asks Lucius for a recommendation and is quickly installed in the Ministry's Department of Mysteries, joining his cousin Claudius there. The work suits him, though the reality of working for another person often doesn't. He also relocates to his father's estate in Kent, which had been entirely abandoned since the man's imprisonment.

His new career means he is present when the Ministry collapses in on itself that spring, and Tiberius is left crippled and scarred as a result. Not one to accept such ready defeat, he finds a way to restore his body to what it once had been through the use of dark magic. This requires the murder of several innocents, which his sister—on temporary loan from his aunt's finishing school—cheerfully assists with. #LestrangeBonding

He is entirely sound of body by the time his betrothed graduates a few months later, and Tiberius weds Miss Antigone Baudelaire that July. His wife is a rather tiresome one, though she does grow on him slightly over time, in an antagonistic sort of way. One of her least attractive qualities is her propensity to get into public duels, one of which sees her interred in his aunt Olivia's finishing school in the spring of 1886. That comes to an abrupt end when the two discover Antigone is pregnant, and she gives birth to twin girls in September of 1886.

That December, Antigone runs away. Rather than expend any effort to look for her, Tiberius toys with the idea of having her declared dead, but her return a few weeks later makes this unnecessary. Instead, he forces her to take an Unbreakable Vow to ensure she behaves in the future, with his sister Tatiana acting as witness. Despite this setback, their relationship slowly begins to improve over the course of the coming year, with Tiberius offering to teach his wife legilimency or dark magic as her interests dictate.

When Antigone announces she is pregnant that spring, Tiberius attempts some magic to determine the gender of the baby. It appears to be a girl, and since he has no desire for a third daughter, he attempts to poison Antigone to the point of miscarriage. This very nearly results in her death, but he is able to bring her back from the brink. Possibly because of his interference early in her pregnancy, the baby she delivers in September – a boy – is deformed. Antigone attempts to murder their son before he can see, but the labor has left her weak and Tiberius ends up finishing the job.

A consultation from a healer implies that Antigone will not be able to carry another child to term due to the damage suffered during this most recent birth, and Tiberius is at an impasse. He discovers with some surprise that he is very hesitant to dispose of Antigone. She offers to raise his bastard as her own, if he is able to procure a son through alternative means, and the two uneasily move forward with this plan. In the meantime, Lucius strongly implies that perhaps his two living twin daughters have something to do with his family's "bad luck," and Tiberius sets about the remedy that problem. After trying and failing to solicit his wife's opinion on which twin they ought to keep, he sends one away — but refrains from killing her unless he picked the wrong one. After an emotional confrontation, Antigone eventually proposes that they continue living under the charade of one twin having died and watch them grow separately until they can determine who the superior twin is.

Tiberius talks to his cousin Cassius and implies vaguely that Lucius will likely kill him sooner or later if he doesn't prove himself useful, since he has a healthy infant son now. He proposes that Cassius find a girl to marry, and let Tiberius handle the actual consummation/et cetera — with the trade off being that Tiberius is going to steal the first male offspring and raise it as his own. His cousin, although not understanding Tiberius' reasoning and a little skeptical of the plan in general, agrees — but is painfully slow about selecting a potential bride.

Tiberius' life goes on as scheduled until Antigone manages to complete an animagus transformation, which he hadn't even known she was seriously working on. Not wanting to be one-upped, Tiberius devotes more and more of his time to the study until he has nearly become obsessed. He takes an impromptu sabbatical from his work at the Ministry to focus on it (and, since this happens in the midst of a national crisis, sees himself abruptly relieved of his position as a result). After one failed but not fatal attempt, he manages it and his relationship with Antigone returns to cold-but-not-worse-than-usual.

The turning point in his relationship with Antigone is when the woman paid to watch the spare twin decides to try and extort Tiberius for more money in the summer of 1889. Not willing to put up with that, he asks Antigone to choose which twin she wants so that he can get on with killing the other one. Rather than decide, she proposes that they send one to the Home for Inconvenient Children, so that when they do kill the extra child they can make the other one watch. Not expecting this level of spite from her but unexpectedly turned on by it, Tiberius agrees (and also starts screwing his wife more vigorously and regularly).

These efforts result, unexpectedly, in Antigone falling pregnant in early 1890. This was supposed to be impossible and Tiberius is convinced it will kill her, so tries to convince her to abort the baby via poison, which Antigone is reluctant to do. Also, Cassius still hasn't found a bloody girl yet. Ugh.