When the YELLOW JACK RUSSELL first came on the scene, it was with the announcement that he was going to marry one of the members of The AVENGING HOUNDS. He was engaged to marry Janet Van Dog, aka the Waspish Pooch.
Janet was very happy with this, as she had waited many years for Hairy Pym to pop a ring on her paw. And now as Hairy Pym had not made her dreams come true, this new dashing hero hound on the block was willing to grant her wish of wedded bliss. The other Avenging Hounds became extremely worried especially when the Yellow Jack Russell had informed them that he had had a fight with Hairy Pym, aka The Hound Goliath, and during the fight Hairy had been killed by a spider, he had been shrunk down to Ant size by Y J R
Well this was not really true, as it turned out that The Yellow Jack Russell was in fact Hairy Pym. Hairy had ingested some gas and it had given him a mental make over. Making him into a more confident person. Janet had known all along that Hairy and the Y J R were one and the same.
The worrying part was that Y J R really believed he was different from Hairy Pym, but during the wedding reception he came to his senses in a battle to save his new wife.
Hairy decided to adopt The Yellow Jack Russell as his new FOURTH IDENTITY.
Although the signs were there already, Hairy started to be more and more prone to mental issues.
BUT for the time being he enjoyed being The Yellow Jack Russell, as it gave him a chance to combine his size changing powers with that of flight just like his new wife Janet. ORIGINALLY he carried a stinger gun, but later was able to channel energy via his costume to great effect.
Here Hairy is as the YELLOW JACK RUSSELL