There are a few candidates for this and they all have varying levels of evidence.
Varys and Illyrio are obvious choices for clear reasons: They're both stewards/magisters/whatever and both of them are untrustworthy, at least where Dany is concerned.
Then there's Reznak, who is Dany's suspected candidate. Because he's her suspected candidate, it probably is not him. (The joke where Reznak is concerned is that he's one of the people Dany trusts least, when he hasn't actually done anything to really warrant distrust. On the other hand, the Green Grace and the Shavepate are both pretty genuinely untrustworthy, but neither of them is as much a target of Dany's suspicion. Have I mentioned that Dany is an idiot?)
Then you have the ship, Selaesori Qhoran. This is actually my favorite option because it's the one the fewest people suspect. Most probably either take Dany at face value that it's Reznak or assume it's Varys.
Now, it being the ship rubs some people the wrong way given that it's no longer heading toward Dany and that its passengers, namely Moqorro and Tyrion, are covered elsewhere in the prophecy, making the ship seem redundant. Quaithe seems to have been telling Dany what she saw at that given time (i.e. Quaithe saw people who were en route to Dany, not making a values judgement on whether they'd actually arrive). So the ship not making it there doesn't mean it couldn't have been in the vision at the time Quaithe gave it.
It's possible that there's something "off" about the ship itself, independent of its passengers. The clue might be in its manifest: tin and iron, Myrish lace, wool, jars of peppers ... and a pickled corpse.
He could be, but I don’t think so. First of all, it’s a bit far-fetched to call Varys a seneschal. The only people in the A Song of Ice and Fire who have this title are the Archmaesters who take turns governing the Citadel, Reznak mo Reznak (Seneschal of Meereen), and Garth Tyrell (Lord Seneschal of Highgarden). Varys isn’t responsible for the administration of a royal or noble household, he’s the spymaster and a small council member. Also, Daenerys would have no reason to trust Varys in the first place, given that she knew the role he played in the assassination attempt against her—Jorah told her he had been sending information to him. Why would Quaithe feel the need to warn her about a person she most certainly considers an enemy? Last but not least, Varys is not on his way to Meereen, and Quaithe seemed to include in the prophecy only people heading towards Dany.
Illyrio is a better choice, because Dany remembers he took her and Viserys into his manse as guests and also brokered her marriage to Khal Drogo. If Quaithe considers him untrustworthy (and he is, since he backs Aegon, not Dany), she has every reason to tell her to be careful. Marwyn is also a better choice: he travels on the Cinnamon Wind (cinnamon has a distinctive smell) and, being an Archmaester, he has most probably served as the Seneschal of the Citadel.
I don't think so.
I think that he is covered with the "mummer's dragon".
The perfumed seneschal seems to be the hardest one to figure out and I REALLY do not think that it is the boat. Reznak seems like the obvious choice too (though he shouldn't be trusted at all), which makes me think that he isn't it.
When Tyrion and Moqorro are on the "stinky steward", Moqorro is telling Tyrion the meaning of the boat's name and he mentions that it could mean steward, seneschal, or magister.
There is only one perfumed magister that I can think of and that is Ilyrio. Dany thinks that she can trust him to some degree but she can't. He has tried to kill her already and all her wants from her is her dragons and name.
Ilyrio is NOT to be trusted and should be avoided at all costs. He keeps trying to get Dany to come to him and I really think that this is who Quaithe is talking about. He never tried to protect Dany and Viserys and he doesn't have "debts of affection" for Dany, he only has them for his son, FAegon.
South Berry Recruit Jacobs North Wild Marc Crossbody Thanks for the A2A!
is the name of the ship on which Tyrion and Moquorro are travelling. This name is translated as Fragrant Steward” - close enough so far!
What on this ship can be in any danger for Danny?
Tyrion and Moquorro are long off the board at the time the ship is supposed to reach Mereen.
Lets take a look on the cargo: "Two days from now, the cog Selaesori Qhoran will set sail for Qarth by way of New Ghis, carrying tin and iron, bales of wool and lace, fifty Myrish carpets, a corpse pickled in brine, twenty jars of dragon peppers, and a red priest. Be on her when she sails."
…a corpse pickled in brine…
Why a corpse must be pickled? - For preserving of course!
Do we have another dead body tossed around ship’s cargo spaces?
Marc Jacobs Berry Wild Crossbody Recruit South North “Quhuru Mo would not allow a funeral pyre aboard the Cinnamon Wind, so Aemon's corpse had been stuffed inside a cask of blackbellyrum to preserve it until the ship reached Oldtown.”
When Cinnamon Wind reached Oldtown it directly start to travel towards the Slaver’s bay bringing Marwin to Danny.
So we have one pickled dead body traveling from Oldtown to Slavers bay and one other traveling from Quarth to New Ghis. :) Coincidence?
So what i think is that the real danger dor Danny here is the dead Aemon - body preserved so it can be used for blood magic - blood magic for stealing dragons!
As I understand it, a seneschal is some sort of steward, someone who oversees the administration of a noble house. Varys is not a seneschal, he is a spymaster. So I find it unlikely.
The usual suspects for the "perfumed seneschal" are:
Garth Tyrell is half a world away from Dany and a quite minor character, so it seems quite unlikely it refers to him.
The Selaesori Qhoran was my initial bet but now the ship herself is not important any more. It could still mean she should beware the people who used to be on the ship (Aegon and his retainers, or Tyrion, or both), but then it would be a poor piece of advice : now Tyrion has been kidnapped a while ago and Aegon is in Westeros, and I really don't see how Daenerys could possibly come to learn the name of a river boat they used to use at some point.
On the other hand, Reznak mo Reznak is still at Mereen and still a perfumed seneschal, so now my bet is on him.
Possibly, as he is perfumed and he is a seneschal; nobody can say for sure, however.