You had to run away after Jiraiya used his technique, coming to save Naruto. Itachi used Amaterasu to free you from the trap of the Sannin technique and it was the worst option even though you had no choice. You had already seen him do it and knew how he would feel after that.

You have failed your task, and if you have to seal another Tails now, it will be years before the next time. You were a renegade from another village, joining the Akatsuki before Itachi, and then you were made partners, and that's how you've been together for several years. Itachi didn't speak much, was mysterious, quiet and eternally calm, but when he did speak it always felt different.

You didn't know everything about him, only a small part, that was enough, you already had a strong relationship as partners. The two of you were far from Konoha now, you noticed how his legs were barely shaking and quickly stopped, finding a quiet place to rest. Itachi shuddered with a coughing fit, covering his mouth with his hand as he lay on his cloak in the shadow of some cave. This battle exhausted him even emotionally, after a brief meeting with his younger brother.

You wanted to help him, it wouldn't be bad to start a fire, dark clouds were gathering in the sky, there is a small village not far away, you could get food there. You said you'd be back soon, covering him with your cloak, wiping the blood from his lips before leaving him alone.