Long story short...mom & dad rescued a stray. He is FIV/FELV negative(tested twice) treated for fleas, Giardia& roundworms & was nuetered yesterday. He's very affectionate & seems like a great cat about 1.5 to 2 years old. We have 3 males that love each other & get along now, but are willing to try to add him to our happy family. We have him in a separate bedroom & also have a gate that has a clear plastic window so they can see each other. So, Marley (our youngest & super friendly cat peeked at him through the window gate tonight. Mccoy(our stray) ran up so fast to the Marley & tried to get his claws through the sides to grab at him. There was no hissing, no growling on either side. My husband was on the other side & I was on the inside of the gate. After that, McCoy sat down & did nothing next to the gate, and our other tuxedo (another sweetheart that loves other cats) came up and squeaked at him..almost like saying hello. So, that was it for today, and we shut the door. My only concern is that why did McCoy go low to the ground and run to the gate fast to stick his paws out? Is this aggression or just saying hello??:?