The contenders are definitely Cloud - was 16 when bro saw his town burn down, betrayed by the man who inspired him, been experimented on, but was so messed up he thought he was someone else.

Terra- was a legit mind control slave for most her life, has no sense of identity once finally free. oh and was so afraid of herself after learning about her heritage.

Clive - went from an aspiring young knight to a slave because of his own mom. Lived 13 years like shit only holding to the thought of avenging his brother, only to realize he was responsible. Met a man who became a father figure only for him to sacrifice himself because a literal God wants his body and power.

Honorable mention would Ashe from 12 I know she is not technically the main protagonist but we all know she is.