In a season of plentiful twists and turns, the fifth season of Arrow has managed to provide long-time (and new) viewers a strong overall season thus far. Prometheus has proven to be a solid villain, the additional members to Team Arrow have added plenty of previously-missing personality, and the entire season has maintained a good sense of fun and stakes.
Those stakes have come in the form of interesting flashbacks involving Oliver's time in the Bratva, Oliver's new role as mayor, and the new Team Arrow taking on serial killers, psychos, and all sorts of baddies. Although there's no supernatural-powered being like Ra's Al Ghul or Damien Dahrk, Prometheus has proven to be more than a handful and has contributed to some of the remaining tension left to resolve within the few remaining episodes.
With that said, there are some questions that fans have regarding the future of the show, as well as what's to come as season 5 draws to a close.
At the end of Underneath, Chase is seen walking up to Oliver's biological son William and mentioning that he's a friend of his dad's. This ties in to Chase's previous comments when torturing Oliver and mentioning that he may pay William a visit to bring Oliver even further to his breaking point. Now that Chase has William and sent that threatening video to Oliver, it's clear that Chase has plans with Mr. Queen's son.
The question is, what exactly does Chase have planned for William? It's obvious that Chase has some major plans for Oliver considering the return to Lian Yu and his kidnapping of every Team Arrow member, but kidnapping William feels like overkill.
Chase already has Oliver hooked by kidnapping Felicity and company, so why kidnap William? Considering that Chase is more unhinged than ever, maybe simply breaking Oliver beyond repair isn't enough. He needs to ruin his reputation with everyone in Oliver's life, including Oliver's own son.
After all, with Oliver's limited contact with William, it'd be especially heartbreaking for Oliver to see his son so horrified by what his (unbeknownst to him) father has done/may end up doing to save his friends. Chase has always been multiple steps ahead of everyone, and he surely has a plan with William that will potentially bring Oliver to his breaking point.