paralel process:
assign event Y to any variable u want to use, let's say in his middle position he's in y = 10 he can walk up to 6 and down to 14(skip this step if there are no limits to how far he can walk)
assign a random number between 0 / 1 to a random variable:
conditional branch for said variable, if its 0, move up
if its 1 move down
don't forget to the wait for move completions
now if there's limits to how far he can walk, let's say he's at y = 6, the he has to move down, else if he's at y = 14, he has to move up, else (when he's not on the limits) then ud put the event i described earlier, u check for the random variable, moves up if its smth, moves down if its the other
edit: I wouldn't recommend using too many paralel process, 1 its fine to make a gimmicky character but keep in mind this will be constantly active if ure in that map or close to it