He's not vain enough to think he's taught her everything she knows, but he's taught her a lot of it. She's one hell of a soldier. Devious. Tenacious. Ruthless. She's got the instincts of a predator. There are Admirals that he trusts at his back less than Shepard. She may be young—younger than the Alliance believes, even—but God have mercy on anyone who thinks she's stupid.
So when Shepard wakes up and starts talking about Protheans and ancient sentient machines and mass extinction, he trusts her.
Ambassador Udina doesn't. He's using her to get Saren declared rogue, to get humanity in the Spectres, but he thinks she's just babbling gibberish. Hallucinations from a concussion, like Dr. Chakwas warned. Udina thinks it's suspicious that she's gotten a whole frigate to believe her when she's been stationed on it barely a month. Anderson thinks it's because she's proven herself capable. Dependable. The Ambassador thinks it's because she's conniving.
Udina's always been an ass. Anderson itches to smack that look off his face.
Instead, he steps down. He doesn't want to retire, but if that's what it takes to give Shepard her chance, that's what he'll do.
He waits in the Embassies, completely in the dark, while she runs off to all corners of the Citadel. She leaves with Lieutenant Alenko and that Chief they found on Eden Prime. She comes back with a turian C-Sec agent and the meanest-looking krogan he's ever seen. They've got a jumpy quarian in tow.
The evidence she's got is more damning than anything Anderson could have hoped for.
And just like that, she's a Spectre. She's got the Normandy, and the aliens are following her like she's a damn general. She takes off after Saren, and the only thing Anderson can do is feed her intel and offer advice.
He gets reports of her activities all across the galaxy. He takes vindictive satisfaction from the Council chewing out Udina for Shepard's lack of proper respect. He knows Hackett's constantly giving her missions, and he knows she does as the Admiral asks, because she's too loyal to the Alliance to just wash her hands of them. He knows the Fifth Fleet gives her all its dirty work. She's untouchable, after all. Anderson thinks they're abusing her, especially when things start to get rough, but she doesn't complain.
He watches his acolyte chase Saren's heels, closing the gap.
She finds Benezia's daughter on Therum, in a volcano. There're whispers of some mind-controlling plant on Feros that he only hears about because he's camped out in Udina's office. There's a high body count on that one, but she still manages to save the colony. Noveria is obscured by even more red tape when she leaves. She's cracked a shady administrator, apparently. He guesses that's only because he was in her way; Shepard doesn't care too much for bureaucracy. Reports of the geth make it off the planet. Reports of the Rachni get hushed, though, because news of a living queen isn't going to be stabilizing. Anderson worries that the Council's only waiting until she deals with Saren to declare her rogue.
On Virmire, she blows up part of her team to destroy the genophage cure Saren had cooking.
When she gets back to the Citadel, the Council grounds her. Anderson'll be damned if they think they can screw Shepard like they did him. He knows she's beating herself up about the defeat. He knows she's not going to let that stop her from finishing this.
When he finds her in Flux, she's got a different alien tagging along, an asari. Benezia's kid, he thinks. The krogan is still at her back, and Anderson's sure he couldn't have done what she has. Aliens would not still be loyal to him if he murdered their mother and wiped out the cure for their plague.
She doesn't need a mentor anymore, and it makes him more than a little sad.
Still, he can help her with one last thing.
And Anderson grins, thinking that he'll finally get to punch that smug look off Udina's face.