You were abducted by otherworldly beings (planar, fey, fiend or celestial) Moments later, you reappear, but has physically aged 1d10+10 years, has no memories of that lost time, and has not mentally aged even a minute.
Martial training: In adolescence you trained with the weapons of your people and learnt how to use them proficiently (work with your DM to determine details)
During your early adulthood you saved someone's life. This person becomes your companion. (work with your DM to determine details) Roll 1d10 on a 9-10 your companion falls in love with you.