Drathal was now at the mercy of Drelduin. He had no idea who he was bullying and was about to pay the price for it. Maybe Drelduin would kill him or banish him or worse, banish his father. Drathal's father would kill him if something like that ever happened.
Getting banished from the tribe would mean that they were rouges and all the benefits of being a Delta would be lost. Deltas were the elders of a separate clan, but they still had to listen to Alpha. His father being a delta was the reason Drathal was a bully. He had no fear as his father would always back him up. But now he was going against an alpha.