Much of our knowledge of team newcomer assimilation relies on the assumption that when someone joins a team, each member of the team has similar goals and attitudes. Ha! If you've worked in a team, you KNOW this is not the case. The team might have existing conflict, the team may be dysfunctional, the team might have poor leadership, or all three!
In just published research, my co-authors Danielle Cooper, Shora Moteabbad, Sherry Thatcher, and I pondered over this exact situation. What happens when a newcomer joins a team and comes into contact not just with a supportive, helpful team member (what we call an integrator) but with an incumbent team member that is trying to further his or her own goals in the team at the expense of the team (a GREMLIN!)? Gremlins are particularly destructive not only because they can shape the identity of the team newcomer, but because they can further fracture the team into cliques or subgroups.
Now why would someone be a gremlin? Perhaps it is because they don't believe in the direction of the team, and feel like the team should be doing something differently. Perhaps it is because they feel marginalized, that their ideas are not being considered. Perhaps it is because they've been unable to gather enough support to change a team process, and are in need of more "votes." Either way, to the gremlin, the newcomer is fresh meat. A chance to mold someone unfamiliar with the team in the image of the gremlin.
The organizational problem is that the newcomer likely doesn't know when they enter the team who are the integrators and who are the gremlins! Their motives are to reduce uncertainty - if the gremlin is present, available, and seems knowledgable, the newcomer may struggle, at least initially, to discern whether or not this is someone that should be followed. While this sorts itself out, the team suffers.
So when you are putting together a team or adding a member to a team, make sure you know how each incumbent is likely to engage with that newcomer, so that the newcomer finds the best identity partner possible!