Au Idea
Instead of the big portal that Garmadon opens, Morro ends up escaping form the much smaller on Clouse opened during his and Garmadon's fight in the woods. Morro didn't even mean to go through the portal, he was minding his business, taking a small break after training really hard when the portal opened and he tumbled through.
It breaks up the fight between the men and they just kinda stare at the ghost, both very confused.
Morro helps Garmadon win the fight, but he's more focused on fighting his horrid headache that happened from 1. the bight lights outside and 2. suddenly being forced through a portal with no prepping and after working himself to the bone.
All i really have in mind is that he clings closely to Garmadon, as he still thinks Garmadon is evil and doesn't like Wu, and bc Garmadon is keeping him in check (stopping him from fighting the others, keeping him away form water and bright light, ect.)
When its reveled that Garmadon forged the letter, Morro makes a comment ab how Wu should've put his name on it and that when he read it (either bc Wu showed him or bc he read it on accident going through his scrolls) he felt is was way to sappy for Misako to mistake it for Garmadon.
And while I feel he's tries to fight Lloyd when he puts toghter thats hes the green ninja (it didn't connect when he first saw Lloyd in the green gi, as it was a different gi he was used to and, again, spiltting headache), Garmadon is able to stop Morro from fighting Lloyd. And since he didn't go there with the intention of taking over, he sees this a a little vacation from the Preeminent
I dont have much else but I was watching s4 and i thought of it