Jub was still in a very elated mood from the celebration as the party followed the Misters towards the Hall of Illusions, and that feeling didn't dampen too much even as the two elves explained the situation. He could still sense their reluctance, so he felt this wasn't trap. However, he got the feeling that whatever lurked beyond the mirror must have been something if two warlocks were acting all antsy about it, and this gave the goblin pause.
While he desperately wanted what had been taken from him, was it really worth traipsing into gods-knows-where, with the possibility that he might not come back? Sure, his condition had seriously impacted his life. Part of the reason he had chosen to become a showman was because his previous life of living on the streets and hanging around with less scrupulous individuals had been severely impacted by the fact that no one could trust him to keep his mouth shut, and while performing magic shows for bystanders was a safer and less illegal line of work, it had also proven far less profitable. Still, he was alive, and while some days were way worse than others, it wasn't the worst life. In fact, right at this moment, he felt pretty happy. Shenanigans aside, this had been a good day. He could just turned around, leave and have this whole experience end on a reasonably happy note, no potential threats or danger required.
As he was considering this, however, Tsak spoke up and voiced her desire to the travel with the group, revealing she too had lost something: her family. Jub hadn't been sure what to make of the fairy up until now, but this confession did make him feel some sympathy for her, and in turn reminded him that he wasn't the only one who had lost something. He glanced over at Aurora. She had mentioned losing a ring and a letter, if he remembered correctly. Obviously, not the same as losing a family member, but it must have been of some importance if she had gone through all this trouble to investigate. He then looked over at Gabriel and the human woman, who he realised he still didn't know the name of. He wondered if they too had lost something. He got the feeling the latter had, but Gabriel had been surprisingly tight-lipped about any previous encounter he may or may not have had with the carnival. He was still here though, so there must have been something in it for him.
Then Jub looked at Brutrumukk. Brutrumukk, who had, by his own admission, never been to this carnival before, had lost nothing and honestly, had all the reason to walk away, yet was still here. Quietly, Jub addressed the bugbear in goblin.
"Hey, Brutrumukk, you know you don't have to come with us, right?" he said.
"You haven't lost anything, and we don't know where this mirror leads or when we'll be able to come back." Or
if, but he didn't say that part out loud.
"You said before you just wanted your peace and quiet back, and you can still have that." He knew the possibility of danger was unlikely to deter the bugbear. However, he also knew that the bugbear had little to gain and much more to lose by following a bunch of near-complete strangers into some magical realm, and while Brutrumukk had proven himself capable of heroics and goodness, this would require a level of selflessness that Jub had not really witnessed in, well, anyone.
He certainly didn't want to say good-bye to the bugbear - quite the opposite, in fact - but he also knew better than to expect Brutrumukk to drop everything he was doing and everything he had going for him in order to help people he had only known for a day. Heck, Jub had known people who had been friends for much longer who would not be willing to walk blindly into danger for each other, so he certainly wouldn't hold it against Brutrumukk if he decided to cut his losses right there and then.