Any taxonomy of first friends includes a few familiar types. There’s the amiable glad-hander destined for the outer Cabinet, like George W. Bush crony Don Evans. There’s the scheming, scandal-prone loyalist, like the Clinton hanger-on Harry Thomason, of Travelgate infamy. And then there’s the discreet consigliere who serves alternatively as fixer, sounding board, chief surrogate, and all-around defender of the faith. Personal friends with such outsize influence are actually quite rare in presidential politics. Within recent administrations, only Valerie Jarrett really fits the profile.