the_debt_of_time

Mia, not knowing what her own future had in store for her, worked hard on her
N.E.W.T.s for the same reason she had done so for her O.W.L.s: to break records.
Completely devoted to their studies for the first time ever, Valentine's Day came
and went with little attention despite it being the first the two new couples would spend
together.
James and Lily had gone into Hogsmeade, but only officially as Head Boy and
Girl—although James did take a momentary detour to feed Lily's Sugar Quill addiction.
Sirius and Mia had remained back at the castle to practice for their Defence Against
the Dark Arts practical, showing off their wandless magic by taking turns throwing mild
hexes and jinxes at one another throughout the day.
The only reference to the holiday was that morning when the owls brought in the
post. Despite the fact that Mia had now twice cursed girls in regards to their unwanted
attentions toward Sirius, he still ended up collecting the lion's share of Valentine's Day
merchandise. However, instead of forcing Peter to taste test the potentially poisoned
sweets, Mia flicked her wand, vanishing the whole lot and went about business as usual.
The only time the seventh years let their hair down was for their birthdays.
First, for Lily's at the end of January. James charmed a small flock of starlings—
eighteen to be exact—to deliver flowers to her all day long—specifically, bright pink
Stargazer lilies; one flower for every year since her birth.
Remus's birthday was spent back in the Room of Requirement, this time with
firewhisky but not the Veritaserum. Per Remus's request, an informal Wizards' duel took
place just for fun. By the end of the long competition, Lily had James stunned into
submission, Alice and Frank had called a draw against one another, Sirius had transfigured
Peter into a nogtail and Mary into a niffler, and Remus stood as victor over them all after
sneakily defeating Mia with a Jelly-Legs Jinx—of all ridiculous things.
When the twenty-sixth of March rolled around on a Sunday, Mia and James insisted
on celebrating despite their birthday not taking place until the following day. Monday
meant not only classes but exam preparations that could not be missed. So they turned
eighteen in the Gryffindor common room one day early, sharing butterbeer and stories
with the people that meant the most to them in the world.