[tannhaeuser]

Putting OP's and your clauses together, I get the following pure ISO Prolog program and query that you can paste directly into Quantum Prolog's in-browser execution console at https://quantumprolog.sgml.io/browser-demo/browser-demo.html for execution in no time:

    % Vixen should be behind Rudolph,
    % Prancer and Dasher,
    is_behind(vixen, rudolph).
    is_behind(vixen, prancer).
    is_behind(vixen, dasher).

    % whilst Vixen should be in front
    % of Dancer and Comet.
    is_behind(dancer, vixen).
    is_behind(comet, vixen).

    % Dancer should be behind Donder,
    % Blitzen and Rudolph.
    is_behind(dancer, donder).
    is_behind(dancer, blitzen).
    is_behind(dancer, rudolph).

    % Comet should be behind Cupid,
    % Prancer and Rudolph.
    is_behind(comet, cupid).
    is_behind(comet, prancer).
    is_behind(comet, rudolph).

    % Donder should be behind Comet,
    % Vixen, Dasher, Prancer and
    % Cupid.
    is_behind(donder, comet).
    is_behind(fonder, vixen).
    is_behind(donder, dasher).
    is_behind(donder, prancer).
    is_behind(donder, cupid).

    % Cupid should be in front of
    % Comet, Blitzen, Vixen, Dancer
    % and Rudolph.
    is_behind(comet, cupid).
    is_behind(blitzen, cupid).
    is_behind(vixen, cupid).
    is_behind(dancer, cupid).
    is_behind(rudolph, cupid).

    % Prancer should be in front of
    % Blitzen, Donder and Cupid.
    is_behind(blitzen, prancer).
    is_behind(donder, prancer).
    is_behind(cupid, prancer).

    % Blitzen should be behind Cupid
    % but in front of Dancer, Vixen
    % and Donder.
    is_behind(blitzen, cupid).
    is_behind(dancer, blitzen).
    is_behind(vixen, blitzen).
    is_behind(donder, blitzen).

    % Rudolph should be behind Prancer
    % but in front of Dasher, Dancer
    % and Donder.
    is_behind(rudolph, prancer).
    is_behind(dasher, rudolph).
    is_behind(dancer, rudolph).
    is_behind(donder, rudolph).

    % Finally, Dasher should be behind
    % Prancer but in front of Blitzen,
    % Dancer and Vixen.
    is_behind(dasher, prancer).
    is_behind(blitzen, dasher).
    is_behind(dancer, dasher).
    is_behind(vixen, dasher).

    follows(Last, First) :-
      is_behind(Last, First).
    follows(Last, First) :-
      is_behind(Middle, First),
      follows(Last, Middle).

    order([]).
    order([_]).
    order([X,Y|L]) :-
        follows(Y, X), order([Y|L]).

    ?- order([A,B,C,D,E,F,G,H,I])