who gave the baby aurene mini permission to be that adorable

And Isgarren is an idealist because you kind of have to be one to dedicate yourself to 10,000 years of protecting a world that doesn't even know you exist.

And one of the only things we know about him from before his ascension was that he tried to go help the mursaat fight Zhaitan anyway even after Sidony decided against helping them. Most of what he calls his mistakes were also born from his attempts to help others - taking in Eparch and ascending Waiting Sorrow being the biggest examples. And still he keeps helping others. Still, no matter how many times his attempts to better the world led to another "mistake", led to his own exile from his kin, led to the deaths of people he loved, Isgarren still kept doing it because he believed in doing good no matter what.

He figured out at some point that the Elder Dragons were vital to Tyria's magical ecosystem, so he turned his efforts to fight for the good of Tyria outward, especially once Eparch gave him reason to think all kryptis were threats. He wasn't going to step in with the Elder Dragon wars until it literally threatened the destruction of all Tyria not because he didn't care, but because he had faith in us.

Keep in mind that in the personal story, the Commander and Trahearne successfully united the world to fight Zhaitan. Isgarren had seen this before. He saw Sidony unite all the other elder races to fight Zhaitan, only for them to suddenly betray each other and leave the mursaat and Forgotten to die on their own. The Pact succeeded where the elder races failed. Why wouldn't he believe in the strength of mortals at that point?

Not to overuse and refer back to my favorite conversation in SotO too often, but Isgarren doesn't save farms not because he doesn't care, he doesn't save the farm because he knows the Commander will be there to have his back and do it while he takes care of the dragon minion.

Isgarren, for all his faults and his grumpy and bitter attitude, is an idealist.

Mabon called him naive for a reason. He even calls his own choices naive.

And speaking of Mabon...he's a cynic at heart.

This might seem contradictory to the way he is characterized as an optimistic and positive force among the Wizard's Court and for the Astral Ward (and he is), moreso than Isgarren being a hidden idealist under his sour armor, but consider that Mabon's entire character rides on his idea of atonement.

In his journal from shortly after his ascension, he doesn't remember what he was like before it. He just remembers that his own people are cruel and evil. He assumes Isgarren is avoiding him because he's afraid of him as a violent mursaat and never truly trusted him at all (when this could just as likely be because Isgarren is feeling guilty of the ascension wiping Mabon's memories, but that's just me speculating). He assumes that he must have been just like all other mursaat and he must have been a terrible person himself. So he must atone. And atone he does for 10,000 years.

Isgarren tells you, when you ask him about Mabon, that Mabon was not like other mursaat when they first met.

In SotO, Mabon's arc starts shortly before we meet him. Asthenes is attacking him mentally the whole time, but he puts on his outward mask of idealism and strength to save Dagda and Lyhr and to lead the Astral Ward while Isgarren is missing.

Knowing the Wizards, knowing the Commander, wouldn't we have found some way to save him too? If we knew? If we had realized? Isn't that what the Wizards and the Commander do? Wouldn't we have just made it possible to save Dagda, Lyhr, and Mabon?

Mabon didn't want to die, but he felt at that point "there is no other way this can end" and he outright asks us not to hesitate "when the hour arrives." He doesn't bother to ask for help with his own possession because he thinks he's beyond saving, and he needs to save the others first.

He also notably meddles with Tyrians more than Isgarren does. Many of the Astral Ward's recruits are his specifically. He travels to Tyria frequently to meet people and experience the world "on the ground", so to speak. Compare this to the historical mursaat modus of sitting back and manipulating an entire society unseen.

Even when it's someone Isgarren (and Uenno) recruits like Frode, it's not until Mabon involves himself that they heal and find their place in the Astral Ward.

That's not to say he didn't believe in mortals at all, just that as part of his trying to be a better person than he believed himself to be, he ended up taking it upon himself to help those he felt no one else would.

Finally, it's notable to me that both Isgarren and Mabon attempt to distance themselves from their races in some manner, and they both go about it in very different ways.

Isgarren made himself blue so he might be mistaken for a djinn at first glance but he still takes great pride in being a Seer. He wants to be seen as part of the rest of Tyria despite sitting above it, but will happily answer your questions about Seers.

Mabon hides his wings to be less threatening, but he's still very obviously a mursaat at first glance. He's still other from the rest of Tyria, but he distances himself from the other mursaat so much that he considers his own race extinct with Lazarus's death.