Because in this world, if there was one unquestionable villain, it was undoubtedly the Four Small Vendors—the four guys known as the Chaos Gods.
The Blood God I just mentioned had many names, but the most widely known was Khorne.
Clearly, the man in the Snake-head Armor was a corrupted follower of Khorne.
As for the Lord of Pleasure, the name he was best known by was probably Slaanesh.
In folk tales, Slaanesh was depicted with a goat's head, four arms, and six breasts... Wait, wasn't that just a humanoid nanny goat?
In any case, Lin Yun looked every bit like a follower of Slaanesh.
As for why Lin Yun had immediately taken on this form, one reason was that there was no point in holding back against a boss. That would be far too reckless.
By now, the bandits here were either dead or had fled.
The only ones left were Lin Yun, the man in the Snake-head Armor, and the bruiser behind him carrying an iron slab.
When Lin Yun saw the bruiser and the man in the Snake-head Armor, he had already more or less figured out what his Main Quest was.
And since he might need to use this form again in the future, he decided to reveal it now and see what happened.
After all, if the other man could "accept" Lin Yun in this form, then Lin Yun could keep following the "Main Quest."
But if the guy simply couldn't accept this form, Lin Yun might not have to stick to the "Main Quest."
That would make things much more troublesome, but it was necessary.
After all, Lin Yun didn't want a perfectly good companion to suddenly turn into someone who treated him like the murderer of his own family. That would be unbearable.