Saturn in 6th House synastry is particularly constructive in relationships based on mutual responsibility. The “Saturnian” personality actively helps the Sixth House person to raise his or her professional level and to be more disciplined and organized in general.
The positive aspect of this synastry brings the partners mutual respect and collaboration. If Saturn is negative, the 6th House person considers it too intrusive and oppressing while the Saturnian partner considers his or her counterpart lazy, unreliable, and inefficient in business.
from F. Sakoyan, L. Ecker
Saturn in 6th House Synastry Explained
Saturn in 6th House synastry partners will probably become excited seeing you at work, feeling the urge to lecture you as to what course of action you ought to select and proving that your best bet is to be hard-working and goal-oriented while avoiding distractions and procrastination. You probably won’t be too thrilled to listen to such a lecture, but you may show the partner that you agree, which will make them believe that they found a loyal comrade and assistant whom they can employ as they like.
If you ask your Saturn in Sixth House synastry partner why they think so, they will likely be unable to articulate any legitimate reason, but that won’t change anything for them because they believe this state of affairs to be evident. In the meantime, you could tolerate your partner’s dull and repetitive behavior toward your work due to two main reasons. First, you’ll feel some sort of cold power the partner has over you, and second, because you may stick to believing that this partner may, in fact, prove helpful for you not only in becoming organized and disciplined but in refining your professional skills as well, especially in the ability to go in-depth.
This is exactly what Saturn in 6th House synastry partners are supposed to do; the question is whether he or she takes this duty seriously. The answer depends on (1) how well their Saturn is developed, and (2) how serious your relationship is. If the relationship falls apart, the partner’s partaking in your work may be limited to the same dull carping and insensible dogmatic lectures. However, if the relationship thrives, the partner will carry out serious and important assignments you give them. This will noticeably improve your career and professional standing while the partner becomes more reliable and disciplined. Yet, before this can happen, the partner needs to show a certain level of loyalty and dependability.
from A. Podvodny