Understanding the behavior of these silly pugs

Lola and Logan's dynamics keep me so curious. I have not a clue why they behave the way they do. I'd love to hear your thoughts on why you think they do what they do. I just love to sit back and watch it all unravel.

Here's scenario one:

Logan and Foster Stewie start running around crazy, they stop and mouth each other and sound like gremlins. Lola steps in and grabs Logan and humps him. She is holding him down humping him giving Stewie the advantage over Logan. We have lots of dogs over, Logan plays and she has only humped Logan. Strange - huh?

Scenario two:

We are in the dog park and the dogs are running back and forth wild. Lola sometimes tries to run with them and Logan will run and grab Lola by the harness and make crazy growly noises and whip her around. Then he chases her biting her back legs. Now the funny thing is he only plays this way with Lola. Noone else in the park.

Interesting. Do you think they're still trying to establish who is the dominant one of the two? Mattie hates other dogs, so she's only around Mack and I've not had any experience like that with them. Mack learned quickly, as did Dennis and I, that Mattie rules the house.