After each of them grabbed something to eat, they decided to sit down together to talk a bit more. Erin acutely didn't have to consume blood and could eat a regular diet similar to humans; this was the same for Layla. However, Leo had just grabbed one of the juice boxes with a small amount of blood inside.
Drinking such an amount of blood no longer troubled him when trying to control himself since he was so in tune with his senses, but if a vampire were to deprive themselves of blood entirely for too long, they would feel tired and a little weak.
As for the reason Leo decided to sit beside them, was because he wanted to find out a little more about the sword. He was sure that Layla didn't know how unique it was and would bring it up to her once he found out more.
The two of them got to talking and how exactly a particular sword had gotten into her hands. Even though the match against Burnie was televised, the whole saga of what happened with the second Pure leader was not.