> þeir voru tveir sér

Yes: they were alone together, it was just the two of them. MM & HP:
"Eventually G. and Th. found themselves alone."


> Glúmur mælti: "Án er illt gengi nema heiman hafi. Eg skal taka
hæðiyrði af þér þar sem þú ert þræll fastur á fótum.

> Glúm spoke: `(One) is without bad luck except (one) has (it) at
home. I shall take taunts from you (only?) whereas (when) you are a
slave, fast on (your) feet

Zoega: "ill luck is home-bred". Zoega quotes the version of the
proverb from Gísla saga (án er ills gengis, nema heiman hafi). Note
'heiman' "from home", rather than 'heima' "at home". However, others
have taken 'gengi' to mean "company", cf. the notes in the Íslensk
fornrit edition: Í þessum orðskvið merkir gengi sennilega: föruneyti.
"In this saying, 'gengi' probably signifies: company." [
http://www.usask.ca/english/icelanders/proverbs_BNS.html ]. The
various translations cited on the proverbs page (English, German and
Danish) agree with the ÍF interpretion. And MM & HP: "The worst
companions are brought from home." Gwyn Jones in his translation of
Hoensa-Þóris saga (ok án er illt um gengi, nema heiman hafi): "A man's
worst company comes from home."

ÍF notes: Forsetningin án gat að fornu stýrt hvort sem var þolf.,
þáguf. eða eignarf. "The preposition 'án' in Old Norse could take
accusative, dative or genitive case." See also the proverbs page for
Gísla saga [
http://www.usask.ca/english/icelanders/proverbs_G%CDS.html ], where
'án' takes the genitive. In the version of the proverb in Njáls saga,
it takes accusative: 'illt gengi'. I think 'um' in the version from
Hoensa-Þóris saga = "as to", "in respect of".

ÍF notes: fastr á fótum: ófrjáls, bundinn; orðasambandið þræll fastr á
fótum er alþekkt "with fastened feet: unfree, bound; the collocation
'thrall fastened at the feet' is well known". MM & HP: "a miserable
slave." That is, not implying that he's literally in fetters at that
moment, just intensifying the humiliating idea of being a slave. Was
it used in legal texts I wonder?

> Eg skal taka hæðiyrði af þér þar sem þú ert þræll fastur á fótum.

He's being sarcastic here: "(Oh right) I'm (really) going to take
insults from you (= I'm not going to...), seeing as you're a slave in
fetters." MM & HP: "To think I should have to take insolence from
you, a miserable slave."