Why was Lot afraid to escape to the mountains?
Rashi: He was afraid that his rescue from S'dom was due to the fact that, compared to the people of S'dom, Hakadosh-Baruch-Hu considered him a Tzadik, 1 but that, once he arrived in the vicinity of Avraham, he would be considered a Rasha, and he would suffer 2 the same fate as the Sedomians. 3
Mishnas R. Aharon 1 p.149: Before, Lot went with Avraham and was not harmed! Now that he sees that he is saved in Avraham's merit, surely he will learn from him and be a total Tzadik! Rather, there is great ruin in separating from Torah. Once Lot separated from Avraham, "the crooked cannot be fixed." He cannot be Avraham's Talmid like before.
Much in the same way as the Tzorfatis explained to Eliyahu (See Melachim 1, 17:18).
