Madness
If he (a word used here to describe his usual state, rather than an accurate representation of the reality of the man) was honest with himself, Emporio Ivankov would say that following Monkey D. Luffy is an absolutely mad thing to do. Which, by extension, means that Ivankov was going mad himself. Admittedly, by most people's standard of `mad`, being a giant cross-dresser who weaponises winks, changing people's gender whether they wish him too or not, and, despite having complete control of the human body from his devil fruit, choosing to look like, well, Emporio Ivankov, he already is mad, but he ignores this.
The madness that came from following Luffy on the other hand, well, even he could see this was problematic. Luffy was the kind of man who would willingly attempt to smash his way through an opponent who could melt his body. When Ivankov first saw him, lying there not so much as half dead as dead but hasn't admitted it yet, he regarded the boy as mad.
So why was it, exactly, that soon after this meeting, he found himself attempting the exact same feat? It was Luffy's madness. It was contagious. He had never met Ace, and his one brief encounter with Whitebeard had almost left him dead, but he still wanted to save the guy!
Looking around, he saw the madness was spreading. Buggy was now actually acting like he was going to do something, which may have been helped by the stupidity of the ones following him. Mr 3 snuck up onto the execution platform right under Sengoku's nose for the sake of Mr 2. Mr 2 had stayed behind at Impel Down to let them escape. Heck, even Crocodile was in on it, attacking Admiral Akainu, despite the fact that the man had just killed another logia user and it was highly likely that lava would melt sand. (Unknown to him, Hancock was also being crazy because of Luffy's presence, attacking marines despite the risk to her people, but her normal attitude was so strange and violent you couldn't tell if she was going crazy or just enjoyed kicking people).
Yep. If that boy reached out a rubber hand to you, be prepared to do stuff you normally would have regarded as bizarre. If you ally yourself in anyway with Monkey D. Luffy, he would worm his way into your mind, smash your logical thought processes and replace them with the kind of wide eyed determinism that went out of fashion with the end of the silver age of superhero comics.
This realisation, as stated above, is dependent on him being honest with himself. However, that is simply not possible in the presence of Monkey D. Luffy, because you have gone too mad to notice it. And you loved every damn minute.
AN: I'm running out of people to do! :O Anyway, here is Ivankov's. I wanted to do a first person one, but I couldn't do a particularly good one...so yeah.
Anyway...as usual, comments and critique appricated.