you can't hold with the hare and run with the hounds

The phrase "you can't hold with the hare and run with the hounds" means that one cannot support or be aligned with both sides of a conflict or contradictory positions at the same time. It depicts a situation where someone tries to remain neutral or have it both ways, but eventually they have to choose one side or the other. Essentially, it implies that one cannot simultaneously be friends or allies with both opposing parties since their interests or goals clash with each other.