I have this hc where Bart’s 14th birthday happened while they were fighting the reach and stuff so he didn’t even bother to tell anyone bc they were pretty busy. Months later after the invasion Jaime got curious and asked Bart about it and Bart’s like “oh, yeah my bd was like seven months ago” and Jaime feels super bad bc they didn’t celebrate and began to apologize so Bart just explains him that he doesn’t care bc he doesn’t find it important since he has never actually celebrated his birthday bc the whole “humankind enslaved by the reach in the future” thing and he says that Jaime should just let it go.
Except that Jaime doesn’t. So he starts planning this hella big surprise party for Bart’s 15th birthday and he tells everyone and gets them all to attend, so when the birthday arrives Jaime tells Bart they’ll just hang around in Central City eating ice-cream and stuff to at least make it a happy day when in fact Jaime’s tricking Bart into going to his party. Spoiler alert: Bart was so happy and touched he started tearing.