Well, I think Mr. Mistoffelees is a teenage cat, the only one in the 
play.  Too big to be with the kittens, too little to be with the 
grownups, Mistoffelees is desperate to be in the spotlight and prove 
to the tribe that he is ready to be treated like a grownup cat, but 
he doesn't seem to make it work out, and then he acts like a kitten 
again.(see how in the Jennyanydots song, after he noticed it wasn't 
his turn in the spotlight, he stood on all fours and went to the 
kittens?)  I view the Misto-Tugger relationship as one which started 
out in dislike but ended in friendship. Mistoffelees is envious of 
Tugger(well, he does hog the spotlight and gets all the girls!) so he 
sang the infamous"the rum tum tugger is a terrible bore" line.  But 
if you see Tugger's reaction(at least I saw it this way) he doesn't 
look angry or concerned, more like his thinking to himself "I wonder 
what's the matter whith that kid" So he had a tom to tom talk with 
Misto and he confessed that he had always been jealous of Tugger.  
After that, Mistoffelees told Tugger about his secret talent and how 
he knew he could make it big if he could show it to all the Jellicles. 
(I'm convinced that no one knew about him having powers. They did 
look quite amazed and surprised when Mistoffelees did his magic, as 
if it was something new to them. And I think Mistoffelees was about 
to reveal his powers at the beginning of the Jennyanydots song.) 
Tugger then coached him on being the center of attention and gave him 
some tips on how to present his act.  So, of course, he was the one 
who introduced him by singing his praises, giving him that last push 
into greatness.  And after Mistoffelees brought old Deuteronomy back, 
Tugger saw him with that look that clearly said "you finally did it, 
I knew you could!"

As for him and Victoria, I really don't think they feel atracted to 
one another.  They seem more like really good friends or 
brother-sister to me.  The way Mistoffelees interrupted Victoria's 
solo seemed a lot like a friendly, playful joke from two best friends 
who have great trust in each other.
    
by Chloecat