They have won three Olympic gold medals in doubles. They say they want to play in the 2016 Olympics in Rio. But based on Venus' sparse and spotty playing schedule, their run appears to be over.
On May 1, Venus withdrew from the Madrid Open. With her older sister rarely available, perhaps Serena should consider partnering with other players.
A temperamental sort, Serena would probably play better with someone she likes or admires. It would help if he or she had doubles experience and embraced an aggressive playing style. With that criteria in mind, here are the best possible doubles partners for Serena not named Venus.