Nestle-Aland translates as follows:
(12) The Spirit immediately drove him out into the wilderness. (13) And he was in the wilderness forty days, tempted by Satan; and he was with the wild beasts; and the angels ministered to him.
I translate with a slightly different emphasis:
(12) Immediately the spirit sent him out to the devastated place. (13) And he stayed in the devastated place for forty days, tested by Satan; and he was among the wild beasts; and the envoys took care of him.
I believe we should not turn to supernatural explanations if an earthly explanation is possible.
Let me start with the ἄγγελοι of verse 13 who can be heavenly creatures, but human messengers as well, for example delegation members, representatives or envoys. If Jesus is treated well by this kind of people, maybe he is on a mission, and it is his fellow envoys who take good care of him.
Then maybe the ἔρημον is the destination of this mission. The traditional translation of ἔρημον in the NT is ‘desert’ or ‘wilderness’, but the word can describe any desolate, abandoned or devastated place, also through human intervention and/or in an urban context. Josephus uses this word and the related ἔρημία several times in the ‘abandoned or devastated by human intervention’ sense (for example War 2:504, 4:452, 5:573). In War V:25 ἔρημία is used to describe the part of Jerusalem that had been laid waste by fire during the civil war. Similarly the ἔρημον qualification can also apply to Rome, certainly after the devastating fire of 64 CE. Then ἔρημον can be seen as a cryptic derogatory term for Rome.
This devastated place is the home of Satan, the Roman emperor.
The θηρία, an encrypted name for Roman military, probably are, as they are mentioned together with the emperor, members of the Praetorian Guard.
This explanation may be less crazy then it looks at first sight if we turn to the longer version, for which I use gLuke (4:1-13).
Is there anything in this additional verses that could point to the Roman emperor, the Roman empire or Roman imperial ideology? I believe the answer is positive, and most clearly so in the verses 5 to 8. In verse 5 the devil (not Satan here, but ὁ διάβολος) shows Jesus all the kingdoms of the οἰκουμένη, the Roman empire, and makes a very cynical proposal: he will hand over his empire to his opponent if the latter worships him. This of course is the very last what any Essene or Zealot would do, because ‘we have only God as our master’ was the core of their ideology. Jesus answers with this Zealot creed in verse 8. The Roman imperial cult and the Roman/Essene struggle for world dominion are the background of these verses.
Verse 3 and 4 about the stone and the bread can also be seen in the light of Roman/Jewish opposition. Maybe the (building) stone is the symbol for the eye-catching Roman construction activity, while the bread represents the basic needs of the people. The ‘stone and bread’ remark of the emperor can also be interpreted as cynical: if your God is so powerful, let him turn our expensive building projects into alleviation of the basic needs of your impoverished people. From Jewish side verse 3 has the undertone of severe criticism of Roman policy.
The extension in gLuke does not have to be historical, but it shows how ‘Luke’ interpreted Mark’s temptation fragment for what is was: a small account of a confrontation of Jesus with the center of Roman power.
P.S. Maybe there is also a play on words between ἔρημον and Ρώμη – gLuke gives ἐν τῇ ἐρημῳ.