[Snape]'s fourth memory: On the [Hogwarts Express], Snape tries unsuccessfully to console [Lily], who is still upset that they made [Petunia] so angry. But, they are interrupted by [James Potter] and his buddy [Sirius], already making fun of Snape, and Snape and Lily leave to find another compartment.
[Snape]'s fifth memory: [Harry] watches as Snape's [Sorting] takes place. [James], [Sirius], [Lupin], and [Pettigrew] all land in [Gryffindor], as does [Lily], though Snape moans at this. Snape himself, of course, is placed in [Slytherin].
[Snape]'s sixth memory: Snape and [Lily] argue about Snape's friends, the [Dark Magic] he's getting himself mixed up in, and his spying on [James Potter] and his friends. When Lily calls James an "arrogant toerag," though, Snape is so happy that he hears virtually none of the other things she says.
[Snape]'s seventh memory: [Harry] once again watches from afar as [James] and [Sirius] taunt Snape, lifting him up in the air, and as Snape calls [Lily] a [Mudblood] when she comes to his defense.
[Snape]'s eighth memory: [Lily], furious at Snape for calling her a [Mudblood] and for his cavorting with the [Death Eaters], refuses to listen to his feeble apologies, and storms off.
[Snape]'s ninth memory: Snape meets [Dumbledore] to request his help in protecting [Lily Evans Potter] from [Voldemort], now that Voldemort has heard part of the [prophecy] and intends to kill the whole [Potter family]. He also vows to do "Anything" in return.
[Snape]'s tenth memory: Snape, despairing and furious at [Lily]'s death, sits with [Dumbledore] and vows to work to keep [Harry Potter] safe, so long as Dumbledore never tells a soul of their agreement.
[Snape]'s eleventh memory: Again in [Dumbledore]'s office, Snape complains about [Harry]'s arrogance, though Dumbledore tells him that his other teachers rather like him. He also asks Snape to help him keep an eye on [Quirrell].
[Snape]'s twelfth memory: After the [Yule Ball], Snape tells [Dumbledore] of his [Dark Mark] growing darker, and of his intentions to stay put (rather than flee like [Karkaroff]) when [Voldemort] returns. Dumbledore leaves him with a cryptic message: "You know, I sometimes think we Sort too soon...."
[Snape]'s thirteenth memory: Once again in [Dumbledore]'s office, Severus Snape casts charms to confine the terrible curse to Dumbledore's hand, after he put on the [Peverell ring] and was nearly killed. With only a year or so left to live, though, Dumbledore hatches a plan: Snape vows to protect the students of [Hogwarts] when Dumbledore is gone, and agrees to kill Dumbledore when the time arrives.