I don't think Vanitas will try to hurt you, but as long as he's civil, I don't see a reason to kick him out if he does visit. [Even if Ven won't be happy about it.] He's....someone full of negativity. For him, fighting everyone comes easier than trying to befriend them.
Don't worry, I'll make sure he behaves. And perhaps with time and seeing and feeling what it's like to have friends and loved ones, he can become as sweet as you are!
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[Going at each other's throats is second nature to them.]
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