Warning! Some things may change from the canon timeline of Attack on Titan! Examples are that Mike Zacharias and Frieda Reiss will not die in this story and etc. Remember that this is a fanfic and I will try my best to explain everything to the best of my ability! With all of that covered, I present the Bio of Y/N L/N!

Speech:
Speaking in their mind ' '

Your Name: Y/N

Last Name: L/N

Hair Color: H/C

Eye Color: E/C

Race: Marleyan

Titan Shifter: Yes (It will be revealed later why)

Relatives:
U/N (Uncle Name) L/N [uncle, unknown status]
Willy Tybur [uncle in law, alive]
Unamed aunt [deceased]
Lara Tybur [cousin, alive]
Fine Tybur [cousin in law, alive)
Alois Tybur [cousin in law, alive)
Bruno Tybur [cousin in law, alive)
Ruco Tybur [cousin in law, alive)

Age:
12 (Year 845)

17 (Year 850)

21 (Year 854)

Height:
6'2 (Year 850)

6'4 (Year 854)

Looks: (Flexible)

Personality: Carefree(To friends and family), Serious(To anyone), Ruthless(In battle)

Skills:
Master of Jeet Kune Do at a young age
Master of ODM Gear
High IQ just below of Armin and Hange

Combat Skills: Jeet Kune Do(Martial Art)

Battle Stance:

Human Scaling -

Combat: 10/10

Initiative: 10/10

Wits: 9/10

Teamwork: 6/10

Intelligence: 8/10

Endurance: 10/10

Agility: 9/10

Stamina: 10/10

Speed: 9/10

Human Ability:
Hardening
Structural hardening
Regeneration

Titan's Bio:

Titan Name: The Mixed Titan

Titan Height: 37.5 meters

Consecutive transformations: 2 - 4

Titan Looks:
Physique (Attack Titan)
Appearance of Wolf (Beast Titan)
Armored plates (Armored Titan)
Jaw and claws hardening (Jaw Titan)

Titan Powers:
??? (Founding Titan)
Strength/Physique (Attack Titan)
Memories of past and future inheritors (Attack Titan)
Structural hardening (War Hammer Titan)
Wolf Abilities/Wolf appearance (Beast Titan)
Explosive transformation (Colossal Titan)
Steam Emission (Colossal Titan)
Armored plates (Armored Titan)
Adaptation (Female Titan)
Jaw and claws hardening (Jaw Titan)
Endurance (Cart Titan)
Enhanced Speed (Jaw Titan) (Cart Titan)

Harem:

Mikasa Ackerman

Annie Leonhart

Krista Lenz/Historia Reiss

Sasha Blouse

Ymir(Paradis Island)

Pieck Finger

Hange Zoë

Frieda Lenz/Frieda Reiss

Origin:
Y/N was raised and trained to be the successor of the Mixed Titan by his uncle, U/N. Eventually, U/N passed down his Titan power to Y/N. Y/N fell to a deep depression with U/N being dead but his family kept on supporting him. After U/N's death, Y/N became close friends with Tom Ksaver. Some time passes and Y/N begins to distance himself from the public with only being with his cousin, Lara. Later on, Y/N becomes friends with the Warrior Unit and he joins them with Lara. Y/N is finally seen to the public again as the "Savior" of Marley.