Perhaps young Hitler, who was a socialist, is close to Lenin and is sent with him on the train to Russia as his connection to the German government. Young Hitler is sent to help Lenin and serve as a middle man between him and German military intelligence. At some point he realizes his incredible abilities in public speaking, as he did working on behalf of the German gov't in OTL. He starts to alter the course of the movement itself, and outshines other prominent Bolsheviks by focusing on cultural issues. He attacks capitalism passionately, pointing out the degrading effect it has had on Europe's culture and tradition. This leads to a schism in the movement between the Hitlerists and the Trotskyists/Leninists. Despite these differences, the Bolsheviks rely on Hitler's ability to garner support among the ethnic Germans living in Russia, as well as those who were otherwise drawn to the Green Armies.
Eventually, Stalin and Hitler team up, purging their movement's leadership of any jews. (Something both of them did at one point or another in OTL) This knocks out Lenin, Sverdlov, Trotsky, etc.
What do y'all think happens after this? Can Stalin and Hitler work together, or will one of purge the other?