🌙𝙊𝘾 𝙍𝙀𝙑𝙄𝙀𝙒𝙎🌙

( 20. ) Party Animal

What single event would ruin this person's life?: getting drunk at a party and then dying during that same party(Morgan and Elijah were at that party, and Morgan and Elijah killed him).
Character is most at ease when: he's in his room
Most ill at ease when: attending a party
Angry when: people gang up on one singular person
Reason for killing (If applicable): he wants to send a message to Morgan, Elijah has long since apologized for being stupid(it was an accident). Morgan knew that he was drunk.
Hobbies: loves reading books or just looking at his phone
Catchphrase: "You can't be the life of the party because now, you're dead!"
Nice! As far as I know, this is a completely original catchphrase. It also matches with Christian.
How they kill: it depends
Weapon(s) of choice: Anything you can find at parties(no matter the age target the party is aimed at)
Target: party kids
Sexual orientation: demisexual pansexual

𝐑𝐄𝐋𝐀𝐓𝐈𝐎𝐍𝐒𝐇𝐈𝐏𝐒 

Mother: Mary Wendale
Father: Jason Wendale
Siblings:Lou Wendale, Frankie Wendale
Other relatives: Tristan Wendale(Jason's identical twin and Christian's uncle)
Relationship status:single
Rivals: unknown
Enemies: Morgan
Opinion of other people in general: y'all seem fake, but I won't tell you.
Matches with Christian's cynical personality.
Does the character hide their true opinions and emotions from others?: For sure!
Person character most hates: He's not really a people person, but hates Morgan.
Person character goes to for advice: google, even though google isn't a person
Judging by how Christian likes spending time on his phone, this isn't a surprise. Plus, Google can give plenty of good advice.
Person character feels responsible for or takes care of: Lou and Frankie
Person character feel shy or awkward around: no one
Person character openly admires: Slenderman
Person character secretly admires: Elijah
Most important person in character's life before story starts: his siblings(Lou and Frankie)
After story starts: his siblings+the pastas (to an extent)

friends/best friends: do various online friends count? Also was in a small book club as a teen, so there were those people too.
Since Christian is more of an introvert, it's not a surprise he made online friends.

Overall, Christian has a realistic set of relationships. They match well with his personality. Some advice is to go more deeper into his relationships. You can mention how they met, what they think of one another, what they do together, and even significant moments within the relationship.

𝐁𝐀𝐂𝐊𝐒𝐓𝐎𝐑𝐘

So,Chris(Party Amimal) was born the oldest of 3 siblings. His relationship with his parents was strained because they forced him to go to parties despite him being an introvert. When he was 13 he agreed to join a book club because he thought his parents wouldn't force him to go to parties, he was wrong. At the age of 21 he went to the party where he died(the venue was near slender forest) and he got very drunk, because he had nothing better to do. He eventually got cornered and died from getting beat over the head many times, and getting stabbed in the stomach. He died from blood loss, and his siblings, upon finding he was dead, gave him a funeral. Elijah decided to attend because he regretted his actions. Slenderman sometimes digs up dead bodies and reanimates them to become a proxy. If they refuse, they're a corpse again. Upon getting reanimated, Chris had just one request, which was to leave his siblings, Lou and Frankie, alone for a bit because he really cared about them. He was also glad they found his body, which Morgan, for some reason, didn't bother hiding. He wanted to scare Morgan and send him a message, so Chris renamed himself Party Animal because he died at a party.

It's a good backstory, but a few improvements can be made.

First, the reason behind why Christian's parents forced him to go to parties. Do Christian's parents love parties, forcing him and his siblings to join them? Maybe the reason why Christian's parents force him to come is because they want to improve his social skills?