I'm afraid it's rather complicated to explain. They were on opposing sides of a conflict back on our world. But the circumstances of that conflict just don't apply here, and there's no reason for them to continue to hold so much animosity for each other here in Luceti.

[At least, as far as Ion can tell. Without Van here, what reason did Arietta have to align against them?]

I don't expect them to ever be friends, but I'm afraid of what will happen if things continue to escalate between the two of them.