He ventures in: let no buzz'd whisper tell: All eyes be muffled, or a hundred swords Will storm his heart, Love's fev'rous citadel: For him, those chambers held barbarian hordes, Hyena foeman, and hot-blooded lords, Whose very dogs would execrations howl Against his lineage: not one breast affords Him any mercy, in that mansion foul, Save one old beldame, weak in body and in soul.
Porphyro's snuck his way into the castle, and sneaking is definitely a necessity it looks like.
That fiery heart of his is definitely on the menu for the castle's inhabitants; all of them would gladly kill him.
Suddenly, our tiara-and-feather crowd have become "barbarian hordes, / Hyena foeman," and if any of them so much as hears a peep out of Porphyro they're going to murder him.
A hundred swords feels a little bit like overkill (literally). In fact, it feels like hyperbole, but the circumstances of the poem kind of make you wonder. While one doubts that a hundred swords could even fit in one person (don't try this at home, kids), Keats's setting is so over-the-top that you kind of think that Madeline's family would probably give it a worthy try. Hey, when you need to off your blood enemy, you gotta do what you gotta do. (Check out "Setting" for more on this.)
And that, for the record, is exactly what Porphyro is: a blood enemy. Our castle-crew's dogs would trash talk Porphyro's "lineage," not him personally. Sound familiar?
That's right, Shmoopers, we have a Romeo and Juliet situation on our hands: two families who hate each other's guts, but whose kids are nuts about each other.
For this reason, the poem describes Porphyro's heart metaphorically as "Love's fev'rous citadel." Porphyro's not just trying to get into the castle, he's trying to defend his love for Madeline with a castle ("citadel") of his own.
Hyenas and barbarians aside, Porphyro's got someone on the inside who can help him out: an old "beldame" (which here means a nurse).
Like our Beadsman, she's described as "weak in body and in soul" (remember the Beadsman's "failing spirit"?), so we've now got the two young, vital lovers and the two old, feeble people—sounds like a party.