He killed Redtail
(Ravenpaw's mentor before Bluestar assigned Tigerclaw as Ravenpaw's mentor)
And found out that Tigerclaw was lying and had to leave to go to Barley
(The loner)
And just bc of that Firestar's life was hard bc he watched Yellowfang die, he watched Bluestar die, Ravenpaw left, he had to protect Bluestar from Tigerclaw, and he watched Spottedleaf die