When climbing out the chasm as Rachel with Clarice, allow Clarice across. Later during
"The Assault" Eric will be killed by Clarice if you keep convincing people not to kill her and bring her along.
While fighting waves of 'demons' in the sacrificial chamber, succeed Eric's QTE against the prologue character and everyone else's. Afterwards Eric will die to Clarice without the player being able to do anything to avoid it.
Make sure to avoid the tripmines that you placed in an earlier chapter. You must remember where you placed these.
Credit to ThePugHybrid for their
guide.