Characters: Childe, Xiao
Childe
He gets more possessive than jealous. He's was aware that you had a lover before him but Childe doesn't really like imagining you with another person.
He tries to learn as much as he can in your past partner without making it too obvious
But at the same he time he doesn't show his jealousy. Instead he makes some teasing remark about your ex that the two of you can laugh about
But Childe will get the slightest insecure if the stories he heard about your ex, describing them as a wonderful person but things just didn't work out. Childe is aware of his role with the Fatui and how it could get you hurt.
It almost seems as if your ex was better in ways. But Childe would never mention this out loud of course, it's just something in the back of his that comes to disturb him and every then and now.
If your ex wasn't such a great person then Childe would promise to take care of you and never commit the same actions your ex has done. He even get really annoyed that your ex has done not so kind things.
Overall Childe doesn't get too jealous as he understands that was in the past. You two make some jokes about it. He might even indulge on telling you some of his past lovers(if he has any).
Xiao
Pretty emotionless when you first started telling him about your past partner and some stories. It's hard to decipher whether Xiao jealous or just didn't care if you had a past partner.
He doesn't get jealous really. He has complete trust in you but that doesn't stop him from asking you why the relationship fell apart.
It's easy to tell when Xiao gets flustered and same can go to showing his jealousy. He tends to become colder. Avoiding your gaze, and being quiet than usual. He may become physical with whatever is causing him to become jealous but since this was someone from your past theres nothing that he cab really do. It almost seems as if he's upset with you.
If you mention how you believe he's upset with you and asking what you did wrong he'll deny that he's upset with you and just a bit bothered by something.
Confront him about his jealousy and you'll be meet with hard cold " I'm not." He is.
If your stories portray your ex as a wonderful person, then xiao would get the slightest uncomfortable by that but wouldn't voice it. He questions how a relationship with a wonderful person end. What if you occurred between you two?
If your ex wasn't greatest or nicest person there was well Xiao becomes protective of you, he already was but it cranks up a notch.
Overall he trust you but becomes a bit annoyed whenever you tell him stories about your ex that make him seem inferior.