1852: Early in the year, Rosaline is born the second child to George Delacey and his Russian wife. The Lassey children all learn English and Russian, and Rosaline is generally quite happy to babble in either.
1857: Rosaline gains a sister, Harriett.
1858: Rosaline demonstrates magic when she is attacked by a goose and makes it explode.
1860: For the first time ever, Rosaline travels to her mother's native St. Petersburg for the wedding of her maternal uncle - it is all dreadfully exciting, even if a few of her maternal cousins poke fun at her for her tendency towards English-isms!
1861: Rosaline's brother, Edgar, goes to Hogwarts in September. In October, she witnesses her first duel while in Diagon Alley with her mother - the duel is impromptu and ill-executed, and ends in hospitalization for both parties, but it is still fascinating. Her mother is mildly concerned by her daughter's newfound obsession with defensive magic. Harriett tends to be the good one.
1864: Rosaline finally goes to Hogwarts, where she is sorted into Ravenclaw. Her best class is Defense Against the Dark Arts - this does nothing to curb her mother's mild concern - and she makes mostly female friends of a similar class and temperament.
1866: Rosaline selects Ghoul Studies and Arithmancy as her electives.
1867: Edgar finishes his schooling and gets a respectable job. In September, Harriett enters Hogwarts, and both of the Lassey girls have nigh-separate social circles - this comes as a bit of a relief to Rosaline! In the fall, she joins the Leisure Sports club for the sake of having a competitive outlet that will not upset her mother; even if she is in dueling club, she's trying to be a good daughter!
1869: Rosaline takes her O.W.L.s. She continues with DADA, Potions, Charms, and Herbology at the N.E.W.T. level.
1871: Rosaline sits her N.E.W.T.s and considers herself a moderate success! She meets a herbologist, Felix Bennett a month or so after her Coming Out Ball; she gains a genuine (if swift!) affection for him and the two are courting by September. They marry at the end of the year.
1872: Hardly a month after marriage, Rosaline discovers that her husband has to move to America for work! She considers it a bit of an adventure and does not resent the move too much, even if she does find life in America to be a bit dull - her pregnancy comes as a relief because it gives her the opportunity to be normal and at the end of the year Rosaline delivers her son, Archie.
1873: Life is far too boring! Felix recognizes that his wife is finding everything to be dreadfully tedious and does not protest (to her face) when Rosaline decides to become a professional duelist with the Dueling Society of New York. Male-style dueling too, which is grand. She travels the country a few times a year to compete; portkeys are great. Felix returns to her bed a few months after Archie's birth.
1875: Rosaline begins to seriously think that she will never become pregnant again.
1876: Rosaline comes to terms with the above; she honestly does not think that she would ever be able to love a second child as much as she does her son, so what would be the point in having one?
1878: Harriett marries.
1879: Felix gets killed by one of his plants! A grieving Rosaline relocates herself and her son to Bartonburg, where her family has been living since 1877 - being close to her family is good for her and for Archie.
1880: In half-mourning, Rosaline begins to volunteer at Hogsmeade Hospital. She is good at potions and picked up some obscure-but-useful herbology knowledge from her husband; besides, she needs something to do with herself that isn't a full occupation, because she wants to be there for her son without being bored out of her mind.
1881: Rosaline begins trying to invent defensive spells. Related: Rosaline accidentally lights her kitchen on fire. No one is injured, but her cook does judge her a bit. Archie thinks that this is all dreadful fun; that is probably part of why Rosaline justifies continuing her experiments.
1881-1883: Rosaline lives an exceptionally quiet life, mostly because no one notices her tendency to fail to invent spells in her basement.
1884: Archie goes to Hogwarts and Rosaline acquires the job as Ravenclaw House Matron; she is comfortable with taking a real profession now, and would like to keep an eye on her son. Besides, she's qualified. She makes the acquaintance of Professor Nikolai Sleptov.
1885: Nik and Rose kiss under the influence of love potion over the summer. After her house burns down, she and Archie stay with the Sleptovs over the Christmas holiday - and Rose takes things several steps further with Nikolai.
1887: Rose and Nik are discovered, so to speak, by his daughter Eva. Yikes. At least she doesn't reveal anything to anyone. As long as Ustinya doesn't find out, Rose thinks things will be fine.