Vriska Serket, whose lusus constantly demands she feed it, received Cetus as a denizen, a monster known for eating every single fish on the Land of Light and Rain.
More obviously the number 8 is homophonic with the word ‘ate’ (and also takes the shape of the infinity, related to the ouroborous symbol depicting a snake eating itself), and in Homestuck’s symbology the sun - the symbol of the light aspect - is something that is meant to be ‘eaten’ by black holes.
Generally speaking the light aspect and its players could be said to be connected to greed, and a struggle against it.
While Cetus doesn’t appear to relate to Rose personally in the way a lot of the other denizens do - Typheus and John’s Dad share a connection to pipes, as do Hephaestus and Dirk to swords - she does overindulge in fish in the same way Rose’s mother overindulges in alcohol.
Vriska’s land and nature tie this connection more closely into the aspect itself; the Serket legacy and the Land of Maps and Treasure are both plagued by the desire for the material form of “fortune”, gold and riches.
In this way both Rose and Vriska’s game quests deal with the overcoming of either one’s own greed or the greed of a guardian.