Lightning is the older step-brother of Thunder. Lightning was born with a different father than Thunder. After the first litter, the father abandoned Lightening and his mother. The reason why is because the litter didn't please the mate and he believed it was due to Lightning's mother's past of being unfaithful to her past mates. Along with other problems in her past life. She actually wanted to try to be faithful this time around, to settle without problems. Yet, this didn't happen to the poor femme.
Later on, Lightning's mother found another who would treat her well. The father of Thunder. But she forced her pups, after awhile, to leave her. She didn't want any of her pups to be defiled by her past. The mother would rather see them make a name for themselves and create a better legacy. There were pups who relented. Lightening and Thunder were included, they didn't want to leave their mother.
Come to find out it was the new mate's idea. He said his litter could remain, but he didn't want to keep her past around. It was a tricky situation, since she wanted to be faithful and quit moving to new mates and she somewhat agreed with him. Nonetheless, Thunder didn't want to abandon his step-brother. They had become close in the few years they were together. Even in spite of their contrasting personalities. Thunder is unfriendly toward many while Lightning is sociable to all. So, they left together. The others from the past litter did, too, albeit they left the two brothers for various reasons. One that unified their decisions was that they really had no connection to them like they had toward each other.
Kalani found both Lightning and Thunder. The brothers weren't together at the moment. However, Lightening told Thunder about the new pack that would accept them. They both thought their past defined them, but the Crescent Shimmer Pack showed them otherwise. Ever since, they have served as hunters under the merciful leadership of Kalani.
Stalking"
Hunter