Relationship between type 1 and type 3

The ethical and the chameleon

Mr. Spock (Star Trek)
Mary Crawley (Downton Abbey)

Attraction

These two types have strong points in common, as well as major differences, which make them very complementary.
They value competence, productivity, efficiency, performance, both are guided by the desire to be the best in what they do and help each other to move forward. The 3 may be more sensitive to its reputation while the 1 pays more attention to its principles. The 1 pays a lot of attention to detail while what matters for the 3 is to reach the result.
They complement each other on quite important points. The 1 has a very rigid and methodical approach, while the 3 is more flexible and uses a lot his adaptability skills. The 3 generally have a very active social life and often develops 1's one, while the 1 allows the 3 to have a certain relationship stability.
Both are not very sentimental and prefer to communicate through shared activities and conversations related to their goals than to talk about intimate feelings or deep, emotional conversations.
They both need some personal space in the relationship and are happy to be able to offer that to each other.

Points where to be careful

The 1 can sometimes find the 3 as being too unconscious, immoral, neglecting details, superficial, manipulative, cold and narcissistic. He might despise the tendency of the 3 to completely change its public appearance according to the situation so as to always look good. The fact that the 3 often misleads the others with a false image can make the 1 very suspicious of his relationship.
The 3 can sometimes find the 1 as being too critical and moralistic towards his behavior and to become frustrated. The 3 needs to feel appreciated and admired, while the 1 can be very rigid when he detects imperfections, especially when things go against his principles.
Both may have difficulty confronting emotional problems and both are likely to take refuge in their professional activities if there's an emotional conflict.