Hollow Mind really had Kid Belos who is actually Belos the grown man, act like a whole child, treat Luz like she is his big sis, hide behind her, hold her hand...

My brother in Christ, you are in your 400s, what are you doing??

He really shed all pretense and poise, and acted like a feral gremlin, so unlike how he is as Belos. For some time there he freed himself even though it was used for manipulation. And that child who plays games to satisfy his selfish goals? That's Philip, that's who he really is. At his core, an immature person who refused to grow up like his brother and instead sank deeper and deeper into his "games".