Maybe Rivera has been watching old episodes of Dudley Do-Right of the Mounties.  I have to say that this is an awful lot of melodrama for a situation that has yet to look threatening to Rex:  No locked gates, no 30 foot walls, no deep dungeon, no chains, no knock-out drugs. If Rivera expects us to believe there really is an actual threat against Rex, it would be a good idea to show some of it. A bit of seduction and an arched eyebrow hardly constitute a mortal threat. Frankly, a little seduction may do Rex some good, based on what we’ve seen of his personal life.

Now, I’m not completely sure about the white “cut out” highlighting around Mark in panel 4, except that Rivera must be using it as a visual device to offset his “actual” presence from the “mental image” of Rex and Mark sharing an intimate moment with pet dog pictures. She has drawn several “flashback” scenes, but this is the first one I’ve seen using this outlining.  I don’t think it is very convincing as a temporal border. Rivera would be better off using a large thought balloon, as she has done, before.