Warning! Spoilers for Wolverine #13 ahead!
So if both Deadpool and Wolverine have healing factors that can replenish every inch of skin on their bodies, regrow a limb, and even brain tissue...then do they have belly buttons? In Wolverine #13 Deadpool ponders that exact question as he finally gains entrance into the exclusive Hellfire Gala.
There's no doubt that both of the Marvel heroes have incredibly powerful healing factors, powerful to the point of not caring about blowing each other up when Wade crashes the party in X-Force #20, but there has always been some ambiguity as to how exactly they work. Questions constantly pop up about whether or not Wolverine can get a tattoo, if Deadpool can be poisoned or if Wolverine can get drunk, and so on, but now Deadpool is begging an even more pressing question: do they have belly buttons?
The creative team behind this issue, Benjamin Percy, Scot Eaton, Oren Junior, and Matthew Wilson, do a brilliant job of bringing this incredibly funny and genuinely debated question to life. And although it's absolutely ridiculous that Deadpool is asking it, considering he can just look down and check, it's still an extremely valid question...even if it's asked after suggesting they all take body shots off of each other. Theoretically, it makes sense that they both should have belly buttons considering their powers kicked in later in life for one reason (natural) or another (artificial). This means by the time their healing and regenerative powers activated, their belly buttons were already fully formed scars and a part of their body composition versus being active wounds. But what's stopping their abilities from wiping that scar out of existence after, say, getting themselves cut in half or having their skin ripped right off their bodies, as is common happenstance for both of them? Well, there are a few theories.
One theory, introduced by writer Chris Claremont, is that Wolverine's healing factor causes him to regenerate back to a specific variation of his physical makeup: basically meaning that Logan will always return back to one specific version of himself when injured. Additionally, once again considering the fact that his healing mutation kicked in when he was older, then there's no prior version of himself for the gene to compare to that would signify his belly button being anything other than a normal part of his body. These theories could similarly be attributed to Deadpool, especially considering his healing properties are basically a lab engineered, slightly tweaked version of Logan's.
One big difference between Wade and Logan, other than their personalities, is that Deadpool's regenerative properties affect both his normal and cancer cells, making him unfortunately look like a Freddy Krueger knock-off. He's unable to heal his skin because his normal cells and cancerous cells are constantly regenerating and, simply put, canceling each other out, scarring his entire body in the process. So although he too most likely has a belly button, it probably isn't very recognizable as such given his state. Luckily enough for him, the odds are in his favor when it comes to Wolverine having one, so if Deadpool can somehow find a way to convince the big guy to let him take a body shot off him, then the possibilities are endless.