They are integrated parts of him, though, If he "himself" was be capable of becoming a little aggressive when he felt like it - he would n`t need Thorn...

Is he in therapy?

Have you ever tried to ask Thorn and Sventas where they are coming from? and What do they want?
There are ego alters which are a dealing mechanism...just like i said above about aggression. and there are fuge alters.

There are people who can`t deal with trauma or extreme stress and - especially at night - develop habits of traveling or something...sometimes others don`t even feel it. People with Fugue are found traveling away and often confused about their identity. Now - this usually is said to have nothing with DID unless it repeats itself. Then - a full identity can for from this. ....I just know my Fugue alters...that`s why i say it- ego alters have somewhat different function.

They are all born from the need to survive...to be distracted. That`s the common thing. I agree with lilly leaf.

From their names they sound like they are more of fugue alters - but you never know...just by the name. But if they are Fugue alters they will know. They might awaken and let go...they are very intelligent beings.

I am happy for your boyfriend. BTW i know how it feels to be with BPD and have these horrible attackes from someone loved. You are doing great. keep it up.