Didn’t what to necro so question?

i gave my party a deck of many things and one of them drew Flames.

• A powerful devil becomes your enemy. The devil seeks your ruin and torments you, savoring your suffering before attempting to slay you. This enmity lasts until either you or the devil dies.

i have a bit of a plot planned out Need a bit of campaign help - Dungeon Masters Only - Dungeons & Dragons Discussion - D&D Beyond Forums - D&D Beyond

(I’m taking Lord_Thunderfarts idea by the way) So how do I work in the flames card whole staying true to the story/plan 

The deck of many things is completely chaotic. It can completely derail a campaign, instakill a pc, cause long term effects like your devil, and so on.

As a dm i hate the deck and they do not exist in my worlds, specifically because when a player draws something like a devil card,i now have several sessions that have to have this stupid devil in it. 

If youre the dm and you love chaos, or if you want to dm like a wild magic sorcerer and just roll on tables to see what happens next, the deck of many things is perfect.

But if you introduce the deck and then end up asking "how do i make the chaos less chaotic?" Then the deck may not have been a good idea. 

The devil in question takes control of one (or more) of the enemy pirate clans. Either through a fiend warlock, or maybe it shapeshifts and runs the group directly. 
And since it wants to torment the character, I’d have it focus on that, even if it means otherwise weakening the pirate clan; after all it doesn’t care about the clan’s long-term health.

So maybe it sends one group to hunt down the PC’s family or friends who are not in the party. Maybe it finds a way to bind some of those family and friends to its service. And it will find ways to ruin the PC otherwise. Next time the ship is in port and the party is away, have some people go sink it or start a fire or rob it, or all of the above. Basically any time something or someone the PC cares about is left unguarded, the devil’s forces attack. I might not even make it clear the devil’s forces is behind it. It wants to torment, that doesn’t mean it wants the credit.
And remember a devil is immortal, it’s got plenty of time to keep bothering the PC. I’d let the party decide to hunt the thing down, but I’d never have it just appear looking for a fight.

Quote from cl0ud_stalker_234 >>

So how do I work in the flames card whole staying true to the story/plan  

Well, your core mistake was giving the PCs a deck of many things, as it is the Destroyer of Campaigns, but in this case I'd just add the devil as an ally to one of the groups (probably pirate group 2; devils tend to like merchants and dislike chaos).

Think that these ideas are coming aboard the ship of last minute planning for Dnd

 In the Book of Many Things there is a chapter on handling this card so if you can get a hold of it there's some advice in there and a few fiends that you could possibly choose as an enemy to the card drawer.

Probably tie the fiend in with your pirates somehow. Have the fiend send servants to aid them in destroying the characters, and after a few such buildup encounters the fiend comes to confront them itself, perhaps with a bargain that seems fair but is actually totally ruinating, offering them cursed items, and tries to mess them up in general without engaging in conflict. The fiend fades into the background and tries to make things difficult without directly attacking them. 

It's what you get for drawing from the Deck of Many Things.