Ichika would see red at the Morph Chifuyu that Laura took on. Laura's image of strength was Chifuyu so it makes sense that the VT morph took on Chifuyu's appearance. It was an external 'mind rape' on Ichika - using his sister whom he does love and hold in high regard to literally crush him.
If your own family member whom you look up to suddenly tried to kill you, wouldn't you freak out a bit? And THEN you learn that it's some imposter just messing with you? You wouldn't care any more - you'd kill that imposter for daring to wear the likeness of your family member to kill you and not so much for the kill attempt itself.
There's a good reason/chance that when mind rapes fail, it is usually followed by someone getting their ass kicked.
As for why he suddenly became forgiving and caring to Laura after the fact, I have no clue - not even Jedi are that forgiving... ...unless their mutual respect (ie. U.S.T.) for Chifuyu reasonated with each other and that became the basis of their turn-a-rounds.
