Who is the refugee mentioned here, and what did he escape from?
Rashi #1: It is Og, who escaped from the battle in Ashteros Karnayim (mentioned in 14:5). 1
Da'as Zekenim and Ba'al ha'Turim, from Pirkei d'Rebbi Eliezer (27): It is Micha'el. 4 When HaSh-m cast down the Satan, he tried to take with him, and HaSh-m saved Micha'el.
Gur Aryeh: The word "ha'Palit," with the definite article, implies "the fugitive" that we know about. The Torah (Devarim 3:11) in fact tells us that only Og remained of the Refa'im who had been wiped out during this war (Bereishis14:5).
Gur Aryeh: Why doesn't the Midrash accept the simple explanation, namely, that Og escaped from the current war? If he already had the title "ha'Palit," with the definite article, this implies that he had already escaped once before. It must mean that he remained of the Refa'im (i.e. the Nefilim) that preceded the Mabul.
Why was the wicked Og spared from the Flood?
Targum Yonasan: So that the world should witness the power of HaSh-m.
Gur Aryeh #1: So that Moshe would later be able to kill him (demonstrating HaSh-m's kindness to Moshe and to Bnei Yisrael).
Gur Aryeh #2: Og was descended from Shamchazai, an angel who had descended from Heaven (see Nidah 61a). Because he had a G-dly aspect, it was fitting that Moshe, man of G-d (Devarim 33:1), should exact punishment upon Og, and not by mere water. 1
What did Og hope to gain by informing Avraham that Lot had been captured?
Rashi: Knowing that Avraham would chase after the four kings, Og anticipated that he would be no match for them. Consequently, he would fall in battle, at which point Og would take Sarah. 1
Why was Avraham called, "Avraham ha'Ivri"?
Rashi: Because he came from Aram Naharayim, which was on the other side (me'Ever) of the River Peras. 1
Seforno: "Ivri" means descended from Eiver. This is why the refugee (who is not named) came to inform Avraham. He did not know that Lot was related to Avraham, but he did know that Lot shared with him the beliefs of Eiver, the grandson of Shem. 2
Bereishis Rabah (42:8): In terms of his belief in HaSh-m, the entire world was on one side, and Avraham was on the other side (me'Ever).
What is the significance of Avraham's three friends here, and why are they referred to as "Ba'alei-Bris"?
Seforno: It was due to the fact that Avraham was currently living in Mamrei's territory (Eilonei Mamrei) that Mamrei and his two friends Aner and Eshkol went to war with him (as we learn later in 14:24). 1
Rashi #1: They had [previously] made [lit. "cut"] a pact with Avraham [to help each other in times of need]. 2
Rashi #2: 'Ba'alei Bris' hints at the fact that they (later) advised him with regard to the Bris Milah. 3
Perhaps that is also what Rashi means.
Gur Aryeh: They were not merely allied. A "Bris," by definition, is not a default condition, but rather must be actively made and accepted, similar to an oath.
QUESTIONS ON RASHI
Rashi writes: "This was Og, who escaped from the generation of the Flood." But the Torah writes, "And only Noach and those with him in the Teivah remained" (7:23)?
Gur Aryeh: According to the Gemara (Zevachim 113b), Og was inside (or beside) the Teivah. 1 He is not mentioned explicitly 2 because he and all of his descendants were eventually wiped out, by Moshe (Bamidbar 21:25).
Rashi writes: "This was Og, who escaped from the generation of the Flood." According to this interpretation, however, the wicked Og lived for more than 800 years!
Gur Aryeh #1: We should not be surprised at his long physical life, because the Chomer (physical) aspect of any being is merely subservient to its Tzurah (purpose) and Nefesh. Before the Flood, HaSh-m's plan for history was still at its beginning, and the beginning of a process has greater stability than the end which follows. Therefore, the Nefesh aspect of the earlier generations enjoyed longevity, and their physical bodies followed suit. (This does not mean that they had a loftier Nefesh, only that they came earlier.)
Gur Aryeh #2: It is possible that "Og" does not refer to one person; but rather to a father, son and grandson, etc. who shared the same name (owing to their same distinguishing characteristics).
Rashi writes: "Og intended that Avraham be killed, and he would then marry Sarah." How do we know that this was his intention?
Gur Aryeh #1: If Og came only to relate the news, the Torah should write, "He came... and told that Lot was captured." Rather, it writes only, "He came and told Avraham," for his sole intention was that Avraham would go out to war and be killed.
Gur Aryeh #2: Chazal teach us that when Og attacked Bnei Yisrael, Moshe was afraid that the merit of having helped Avraham would protect Og. 1 HaSh-m re-assured Moshe, "Do not fear him" (Bamidbar 21:34). Moshe too had been in doubt as to what Og's true intentions were - perhaps he had intended that Avraham should rescue Lot? HaSh-m answered that his intentions were evil, and this event was no merit for Og. Moshe was to deliver his punishment.
Gur Aryeh (to Bamidbar 21:35): Why was Moshe afraid? Surely Avraham's own descendants, the Bnei Yisrael, had more of Avraham's merit on their side? According to the Midrash (Bereishis Rabah 14:6), Avraham is also called a "giant," and is alluded to by the verse, "the great man among the giants"(Yehoshua 14:15). Moshe feared that the giant Og derived some of his great strength from having helped Avraham, and therefore had some connection to Kedushah. In truth, however, while Avraham's giant stature was a reflection of HaSh-m's greatness, Og's greatness was purely physical. See also Maharal (Chidushei Agados, Vol. 4, p. 155).