Karma Drain from Shadow Spirits, My Players: Don't Tell Brian :) Options

[Dashifen]

So, one of my players has a spirit bane for Shadow Spirits. I'm thinking I'm am thusly justified in tormenting him with something appropriate that latches onto him and makes his life miserable. However, if he gets less karma than the rest of the team, I think it'll tip my hand.

Perhaps I should start giving out variable karma ... in fact I sort of want to ... but historically I've always simply handed out the same amount of karma to everyone who makes the session. It never seemed completely fair to play favorites, but without doing so, I'm not sure how I can obfuscate the karma drained by the Shadow Spirit from one of the PCs.

Have any of you used Shadow Spirits successfully as banes? If so, any pointers with respect to their karma drain?

Thanks,
Dashifen