Here's a General idea of what the characters are like (in my view) are like in 30 years (according to my campaign):
Symon grows up and becomes a true champion of Bahamut, bieng much more confident in speaking. Due to an event that I will cover later, he was scarred and became quiet again. He maintains his idea of justice against evil, but he knows that some evils are necessary. His alignment changed from LG to NG.
Nadarr sets up shop after gaining a large amount of wealth, mostly due to he gave up the adventuring life after Olon tore his lycanthropy out of his body, and the event as well. He's the library/magic shop owner in town and the sort of teacher for the casters. Went from NE to LN
Aurel continues to be a wanderer, instilling his Crimson Deceiver side more often. He hasn't changed much, and even though he defeated his father, he never returned to claim his birthright of Talmarune. As always, he too hunts Olon.
Weston and Cromwell ended up working together as a pair travelling planes and hunting Olon. Weston and Cromwell faded into legend as heroes who show up and fix things and leave, one being serious and the other being more of a clown. Both very powerful in their respective fields of magic. Their alignments stayed the same
Karl, after the party finally does battle with Olon, ended up unleashing the full power of his blade, but it held a dark secret, slowly killing its owner as the blade was a holy artifact of many gods of death, and it killed him. He returned years later from death as a revenant, very angry and was never found by the other party members (whom he barely remembers). His death (which actually caused his body to vaporize) made a huge reality check on many of the party members, effecting them. As a blackguard of the Raven queen now, and still clutching his family heirloom, he hunts Olon, but lacks the power to defeat him. He went from TN to NE as his fury against Olon drives him to finally seek that long rest in death. His blade does not harm him anymore as being revenant, the blade doesn't need to kill him.
Alexander still resides in the Abyss, a servant of the chained one. No one knows what happened to him since he last left them. Only Olon knows what happened there.
Archuther was finally slain and put to rest after a long time of being an alive/dead monster. The party destroyed him, and his machinery was destroyed to make sure it didn't fall into the wrong hands.
Thyra traveled the land and after a long period of time of healing, rest and honing her skills, and after a long period of time, spent the past several years traveling with Symon as the two search for Aurel and Karl. She is still NG