Lost Users are those who no longer have any sense in what they're here for. They've lost themselves and lost touch with everyone. These people are also conflicted on what side they're fighting for. Are they a Venkon? Or will they serve Ambrose Malachai instead? They aren't sure.
This can also be part of the stages of being a Venkon, but permanent. When a user is considered to be lost, their status as Venkon is removed. They're too dangerous and unstable to remain on our side. It's hard to forgive, because these incidents have happened with users more than once. It's very dangerous.
Sadly, if a user doesn't escape and fix themselves or finds help, they always end up joining Ambrose. If they manage to come down from it after joining Ambrose, they will be denied entry back in.