One 'trick' of gospel scholarship is to compare similar gospel passages, make a presumption about who is following whom, and deduce some characteristic or another of a gospel writer.
A case in point concerns today's lectionary reading from Mark 10:35-45 (just looking at one aspect). In Mark's version, James and John seek Jesus out and demand seats of power next to the throne. Jesus tips their thinking upside down and they emerge, for the reader, somewhat the worse for the occasion, arrogant upstarts that they were at that point in their careers as disciples. In Matthew's version, the request comes from the mother of James and John (20:20-21) which, most scholars thinking Matthew follows Mark, raises the question whether Matthew is safeguarding the reputation of James and John. Obviously they do not emerge with complete credit from the occasion, mummy's boys that they are (!!), but they are not as power and status hungry as in Mark's account. But is Matthew safeguarding their reputation?
I suggest it is hard to tell. It is possible that Matthew has better access to the reality of the occasion than Mark, so the mother asking is a more accurate reporting of what happened. But it is also possible that Matthew is concerned for the two brothers' reputation, writing some years after the event, in a time when James' lustre as a martyr for the faith is shining brightly, and John's mana as a senior apostle is growing.
Intriguing then is Luke's account of Jesus' teaching servitude to his disciples. In Luke 22:24-27 this conversation (or one similar to it) is placed later than Matthew and Mark, in the discourse at the Last Supper itself; no request is made by anyone, rather a general dispute breaks out as to which disciple is the greatest; and the names of neither James nor John (nor any other disciple) appear in the account.
Is Luke even more concerned than Matthew about the reputation of James and John? Does he edit the Markan account to make a point in favour of the later apostleship of Paul, namely that none of the Twelve was greater than another? Is Luke dealing with another conversation, similar to Mark 10:35-45, and chooses to omit a copy of Mark 10:35-45? (If so, then the question of whether Luke is saying anything about anyone's reputation remains in the air!)
When options have been canvassed we are left (I suggest) with a great deal of uncertainty as we try to guess the intentions of the gospel writers on some matters.