Kakashi is no longer his jounin instructor, but the man still takes him aside once a week for advanced jutsu lessons. On occassion Sasuke will take on solo D-rank missions for the chance to practice something and give himself a break from the old men pretending to be paternal figures in his life.
The council could have assigned Sasuke to Kakashi. the man had the only other Sharingan in the village after all.
It's only halfway through the second year that Sasuke becomes grateful they didn't. He's ashamed it took him that long to understand the priests 'underneath the underneath'. Of course Liam isn't going to teach him advanced jutsu or ways to awaken the magenkyo. Certainly he won't teach Sasuke how to kill or poison. Priests don't do these things. The good ones at least.
They heal. They preserve. They counter the agents of sickness, depression and evil and in doing so Sasuke learns so much more about how venoms and toxins work, how the bod reacts over long term stress, how the mind can break down and the soul crumble when faced with the imballance of hope and possiblility.
Liam teaches him wards and seals, ways to purify or contain evils, ways to shield and protect. once Sasuke master these, he turns the lessons around in the relative privacy of his family compound. He re-engineers the wards as traps, he learns how to dissable or bypass the seals, he creates new jutsu to counter the chakra pattterns and develops compounds that mask themselves as benign medicine.
By the third year Sasuke understands what his strange teacher has been trying to tell him. He knows that his goal, his purpose, can not *end* with his brothers death. He needs answers. He needs truth. If the truth behind Itachi is only that he never cared at all, went mad and ended the clan to test his strength... it is still not the entirety of the truth. Like the truth that one poison can be nuetralized with another is not the whole truth of either substance.
The council could have given Sasuke to Kakashi. They are both Sharingan, and they are both powerul, genius, and fundamentally broken. Sasuke can imagine he would learn many things under the Copy-Nin. He can also imagine those things would not be *enough*. they would be shallow lessons with a shallow goal and Sasuke would become frustrated, bitter and possibly forsake the village entire to find a *true* teacher who would give him the power he needed.
Sasuke has no loyalty to the village that holds him as a hostage. The Third and Fourth do not inspire him. His 'team' has scattered.
Yet, the council, for whatever reason, gave him to Liam. Liam who is no ninja and can not teach him anything *of* ninja, anything of Konoha or the Uchiha or the Sharingan. Liam who teaches him to spy through kindness and community, who teaches him to kill and torture through medicine and healing. The priest who gives him candy and wards and seals expecting him to find ways past them, through them, and praises him for his creativity.
Sasuke will know one day why that choice was made, if the council were wise enough to predict the future or foolish enough to hope he cold be weakened and controlled more easily. He is learning all the ways to see underneath the underneath, and to create his own layers. He has no loyalty to Konoha, but he has ties within it and they give him strength, though he did not always know it. His loyalty can not be purchased with coin or pretty words, but with a currency it has taken almost his entire lifetime to comprehend.
The true lesson, underneath all the layers of pain and death and healing and shielding, is about trust. though Liam does not like ninja, and has no love for teaching, he trusts Sasuke. He trusts that Sasuke *will* learn, and will learn more than Liam can teach, will learn to think and observe and utilize what he knows for a good purpose. He trusts that Sasuke will do *more* with his life than merely kill his brother and avenge his clan. He trusts a child he does not know, on the words from a council he does not like, in a village of ninja he does not agree with, because he knows more about Sasuke than any of them from a single half seen battle.
"How could you agree to this so easily, you don't even know me!"
"I heard from your teacher that you had a battle on a bridge once. That you took a blow meant for your comrad. Why would you do that?"
"I... i don't know! My body just moved!"
"Because your body is smarter than your brain, Sasuke-san. You are trying to rationalize a desicision you have already made. The fact is you made it, and now you must live with it. One day you may even get around to figuring out what it is."
"Would you stop talking in riddles?!"
"I'm not, yet."
The disicion Sasuke had made without realizing, the reason his body knew more than his brain, was because he was trying to seperate the two. He believed, and then he tried to hide that belief in concious logic. Now, looking back, it was obvious to him that he'd decided to trust Naruto from very near the beginning. Naruto would never betray him. Naruto would never lie to him. If, one day, Naruto killed him, it would be because Sasuke had become someone who needed to die and so, Naruto had Sasuke's trust. Deeper, beneath the beneath, he had Sasuke's loyalty. Because he *believed* in Naruto, where he believed in nothing and no one else at all.
"Ah!!! Sasuke-bastard! I'm back!"
Looking down from the north wall at the bright orange blob of dusty genin, Sasuke crossed his arms and rolled his eyes.
"Dead last, you're still alive. What a pity."
"Come down here and say that to my face, I'm gonna kick your ass for old times sake!"
"That would imply you've ever beaten me before. At anything. Ever. Besides title of world's dumbest."
Maybe the priest couldn't make him stronger, but if it had been someone's intention to slow Sasuke down the severely miscalculated. Liam didn't need to teach Sasuke strength. He taught Sasuke many ways to teach it to himself.