Alright, after reading the last few pages I decided to take the path of a mediator.
First of all, let me say when I read the first few pages I took a heavy, heavy liking to Decken in which I believe my first thought upon seeing page 4 (Mangastream) was, "Man, I wish this guy would join the crew." I also wished there wouldn't be so many antitheses since they seem to change my views of a character on my being so easily manipulated by large words I haven't used myself. So, let's start with my reasons for why Decken could possibly be a candidate and why he wouldn't be so. I've read the chapter a handful of times or so in the last 30 minutes so I will be using clues I believe I've found.
Pros:
-He throws an axe, a very large, deadly looking axe at the princess. If you notice he doesn't throw it to harm her, though. A rose is painted on it, a symbol of love and devotion. This retard is throwing an axe at this lady because it has a love symbol on it. He's clearly just a moron who hasn't really shown any harm toward the princess.
-Next, he seems to add "-I think" to the ends of things he himself believes to be fact. Such as his devil fruit, he says "You morons!! I never miss my target!! -I think!!" So, this adds to the idiot factor, of course. This also shows he may possibly be insane, which could defend some cons, though I won't go there since it's not any definite proof.
-He hasn't gotten a reply back from the princess even though Shirahoshi said she rejected his proposal. There's a missing piece here. I suspect this to have a role later on, even though it's not technically a big issue at this moment. I have some ideas but I'd rather not have this sound too fanfiction-y, or however you would say.
Cons:
-He has that whole "if I can't have you no one can" complex going on, which will definitely be a problem unless some random, unforeseen thing goes on, which is unlikely as he does seem as a genuine villain.
-He has sided with Hodi Jones. Another fishman with villainous qualities. They both are determined to kill Neptune, who has been in my opinion one of the most level-headed individuals shown thus far, choosing to simply capture the SH's to find if they really mean to destroy the island, while all other sea-dwellers with the exception of Caimie already want them lynched, more or less. Again this could be a good thing if something of fan-fiction quality were to actually happen. I highly doubt that.
As you see, the cons tend to be more serious while the pros are more noteworthy if they are continued. As we have it now, his chances of joining are at very most ~<1% as he is mostly shown in the context of a villain. The more chapters he is shown in will determine whether that rises or drops significantly. This has only been one chapter, people. It's best not to make such drastic conclusions from a single chapter. As I see it, he has a very small chance of joining right now. Extremely small, basically as insignificant as the smallest flea. I do see a larger chance for a redemption, though I don't write the story. Thus, all these predictions and such should always be taken with a grain of salt, anyways.
Though, no one should technically rule anyone out, since none of us write the story. Oda can do whatever the hell he feels like. He could get halfway into the arc reveal that Luffy was simply dreaming all this up. He could have Decken and Jones fight it out to the death next chapter. He could make the Princess a figment of Sanji's imagination. Sure, they have a .0000000000001% chance of actually happening, but we don't have the final say. If you guys have a time machine, take me back to Woodstock while I happily lug you around on my back the whole time with ear plugs and a blindfold, while I have a bum trip on LSD and a wine bottle halfway stuck up my ass.
Also, troll better. It took you like three pages to completely turn someone away.
