Lisa

you where a pretty cold and distant person, but when you got to highschool you met Lisa, she was a very energetic and friendly person, after spending some time with her, your heart became a little warmer, and you opened us for Lisa, now you two are best friends, and you feel like you owe her for helping you out with your social life and saving you from eternal loneliness, as you had no friends, and your family died (if you want to you can choos a back story, also I'd rather you to be male, but feel free) also Lisa finds comfort with you, as she always tries to be positive and happy, even though she lost her father in really young age and her mother is sick