The first line here doesn’t get enough love! Everyone knows “It’s rotten work” / “Not to me, not if it’s you,” but there’s a beauty in Pylades’ first statement that is very hard to translate and thus doesn’t get enough appreciation (and I’m really grateful that OP included it!)
Euripides’ choice of verb here is interesting. κηδεύω has a few different meanings, all of which are kind of pertinent here. The first, and most basic one, is just “to take charge of,” or “to tend,” and it derives from the noun κῆδος, which means “care” in both an emotional and physical sense. Orestes is currently suffering from a plague brought on by the gods – both a mental and physical one. Pylades is volunteering to tend his disease, and stating that Orestes is an object of his care.
But the second meaning of this verb is to give proper burial rights Pylades says this as he is helping Orestes plan to flee a mob that wants him dead. This is not only a promise to care for Orestes in life, but one that, if anything goes wrong, Pylades will care for him in death.
(The third meaning is less poignant, but it’s a bit of foreshadowing. κηδεύω also means “to ally with by marriage,” and at the end of the play, Apollo does command Pylades to marry Orestes’ sister, cementing a marriage-alliance between the two. So that’s kind of amusing.)
There’s also a bit here that’s dependent on the previous line – Orestes says “I’m afraid the Goddesses would stop me with this madness.” It’s a type of clause that is necessarily not super concrete (this is an oversimplification, I’m not a specialist in the precise conditional weight of a fear clause, and I don’t want to go get my copy of Smyth’s Greek Grammar to check). But Pylades’ response is concrete. It’s the statement “I will take care of you,” not “if that were to happen, I would take care of you.” There’s a world in which Euripides could have easily made that statement an implied conditional and made it less concrete, but this is a promise.
Anyway, the next part develops the bond between the two – but it requires a bit of Ancient Greek grammar explanation. So, in Ancient Greek, like in some modern languages (Spanish, for example), the pronoun of the subject of a verb is contained within the verb. κηδεύσω means “I will care for” all on its own. But Pylades has inserted another “I” at the end of the sentence for emphasis. He’s saying that, no matter what, no matter who else might be with or against Orestes, Pylades will be there.
There’s also some stuff that might be sound like a stretch or over-analysis, but bear with me – word order could be used for lots of things in Ancient Greek poetry (and tragedy is, in complicated ways, poetic). Pylades here is literally surrounding Orestes with himself in the sentence. He’s sandwiching Orestes between two first-persons, literarily embracing him. The apostrophe in σ’ up there also indicates that a letter has been elided – originally, the phrase was “σε ἐγώ”, but two short epsilon sounds one after another were avoided in Greek prosody, and so the first drops out. The result is that the two words that stand for Orestes and Pylades in this are spoken as one word. There’s no separation between them. He’s showing, with his wording, that they’re a package deal.
This post is pretty long already. I just wanted to show appreciation for the near-untranslatable parts of the most overlooked of these three lines, and show just how much depth Euripides can pack into a single “But I’ll care for you.”
Oh, and if anyone is worried that it’s out of context to read this as gay, a dialogue by Pseudo-Lucian (usually dated to the 4th or 5th century CE) says this about their relationship (translation my own): “They took Eros as the mediator of their passion toward each other, and sailed together through life as if on one ship…. Nor did they restrain their erotic love to the lands of Greece, but sailed that vessel to the very last edges of Scythia, the one ill, the other his caretaker.”