Okay, so to piece together what we know so far:
Bluegorge: Lupaz does his thing on his own with the gnolls and the hyenas. Tempest and Vaukriel each do something, it seems like together. Nissa and Oob are definitely not there. Trebuchet we don't know yet, though he seemed more likely than anyone to be a good match for Bluegorge.
Crimelord: Nissa was certainly there, and we have a yes for Oob too. Also Tempest and Vaukriel. We know for sure that Lupaz was not there. Trebuchet also unclear.
So how about this--after Bluegorge, during which Vaukriel and Tempest became friends and traveling companions, they were heading back to the Kingdom of Knowledge at the same time that Nissa was on her way to the small coastal town of Arete in the kingdom, going there to meet a friend, a water genasi she had met previously named Aldri. Unfortunately, Aldri had been abducted and used as a labour and pleasure slave by a gang led by a water elemental crimelord. Vaukriel and Tempest, who were passing through, saw someone else being knocked out and almost kidnapped, and they beat up some of the thugs and saved the new victim, earning the enmity of the crimelord and his gang. Nissa started poking around after Aldri, where she eventually discovered what happened and heard about the brave strangers, so she came to ask their help. Meanwhile, the gang had sent a few sneaks to attack them at the inn, so they knew they were involved in this mess anyway and decided to help. Meanwhile Oob had been exploring a random fun-looking box one day when it got locked up, and he was sad because he was all alone in the dark box. There was stuff inside that looked yummy, so he ate it. When the box was opened, he was in Arete--apparently the crimelord had been smuggling illegal substances, which Oob ate. The gang members decided to make him pay for eating their drugs, and locked him up to torture or possibly kill him. However, Vaukriel, Tempest, and Nissa managed to break up the local gang members and free Oob before that happened. Aldri wasn't there, but they found out where the crimelord's main headquarters was, and discovered that this guy was wanted for all kinds of piracy, smuggling, prostitution, kidnapping, and worse. They managed to corner and defeat him, which earned them the favour of Taala. Since two of them, plus Lupaz, were heroes of Bluegorge, and four of them put a stop to a major criminal organisation, plus Taala liked his little ooze jester, he decided to grant them use of the isle ship (of course, he may have had his own secret reasons too, but if so, obviously we don't know them).
Insert Treb into that wherever Shayuri desires, and it's probably good enough to go on.
But yeah, either way, asking why the PCs are more likely to want to help Lupaz over Vaukriel is like asking why they would try to help redeem a Nymph Blackguard over an Orc Blackguard (or a True Neutral fallen angel vs a Tana'ri)
