Generally in astrology there are two marriage significator planets and they define what type of partner you will get. Jupiter and Venus are the most important planets when we look for married life because Jupiter is the karaka of husband in a women chart and Venus is the karaka for wife in a man chart. By looking at the house in which these planets are placed one can predict about the place where one can meet the spouse and by their sign placement one can predict about the temperament of the spouse. But it gives only half information about the partner.
In Jaimini astrology there is darakaraka. Darakaraka is the planet who has the lowest degree in the chart and it signifies the nature of the spouse. Depending on which planet has the lowest degree the person gets a spouse according to the planet's nature. The sign of the darakaraka planet plays a major role in explaining what kind of nature darakaraka planet has. If darakaraka planets are conjunct or aspected by other planets (whether planet is enemy or friend). If it is aspected or conjunct by a friendly planet then it is going to help the darakaraka planet and the person get a good partner. But if it is an enemy then it is going to harm the darakaraka planet and the person might get a partner who would not be supportive. If the darakaraka planet retrograde, combust it also affects and shows different kinds of nature.
e.g. if The Sun in Aries is a darakaraka planet, then the person gets the spouse who has nature like Sun in Aries. But if there is Sun in Libra sign, then the person gets a spouse who has nature like Sun in Libra. As the planets change sign the nature of the partner also changes. However these are the general behaviors of the darakaraka planet in the chart.
Rahu and Ketu are not considered Darakaraka, because they are not the physical planet.
Following are the results of planets if they are darakaraka in the birth chart and you like to attract these kinds of partners in your life.
Sun is the darakaraka: The person gets a spouse who has Sun-like qualities and these are status oriented, leadership quality, stability, steadiness, pride, creative, capable, and they want too much attention. Jupiter and Mars are the Sun's friends. If the Sun conjunct or aspected by these planets they are going to help the Sun they add the value of these planets. The Moon is friendly to the Sun but in conjunction it does not help but when it aspects the Sun it is going to help. Mercury is neutral to the Sun but it is going to help the Sun. And if Mercury conjoins with Sun it makes Budha Aditya Yoga which means a person is intelligent And they get an intelligent partner. Venus and Saturn are the enemy of the Sun. If the Sun conjunct or aspected by Venus or Saturn then the spouse will create frustration in life.
Mercury is the darakaraka: The person gets a spouse who is very communicative, and friendly in nature. Mercury is a fun loving planet. It is like enjoying more than hard work and commitment. These people get a spouse who is very fun loving and enjoys things in life. If Mercury is sitting or aspected by Venus it is going to help Mercury and the person get a good spouse. If Mercury sits or aspected by Saturn it hurts Mercury. They get a spouse with whom they don’t like to spend time. The Moon is an enemy of Mercury and if it joins or aspected by the Moon then the person gets a spouse who could be emotionally unstable and It's going to frustrate. Jupiter is a good planet. It boosts wisdom, hope, and happiness to the planet with it conjunct or aspect. Mercury with Jupiter is good. It opens the relationship and makes it more enjoyable. Mercury is good with the Sun until it combust.
Jupiter is the darakaraka: The person gets a spouse who is very optimistic and hopeful. These people often get partners who behave like a teacher in their relationships and with others. They are inclined towards those who are very helpful, happy, lucky and cheerful. Jupiter's natural friends are the Sun, Moon, Mars. If Jupiter is sitting or aspected by them it is going to help Jupiter and the person get a good spouse. Mercury, Saturn and Venus are enemies of Jupiter; so they are going to frustrate the partner.
Venus is the darakaraka: The person drawn towards a Venus- like person. They will get a spouse who is balanced, deal maker, charming, social, beautiful, compromising and have a lot of romantic desires in them. They are very romantic and like to compromise with their partners. The Sun, Moon, and Jupiter are the enemy of Venus. If Venus is conjunct or aspected by these planets frustrates the partner. Saturn is Venus friend, but Saturn is a cold and harsh planet and it frustrates Venus when it sits with it. But it is going to help if it aspects Venus. Venus with Mars and gives over passionate nature to the partner.
Saturn is the darakaraka: The person gets a serious kind of older partner who is very committed in relationships. They are least romantic people but very loyal to their partners. These people are not easily adjusted and very firm in their decisions. Saturn is a very antisocial planet and these people are not adaptable. Saturn is reserve, cold, serious and likes to live in reality. But Saturn is very good for long term relationships. They know what they want. They are very realistic in relationships and they choose the right partner in their life. Saturn is the enemy of Sun, Moon, and Mars. If Saturn is conjunct or aspected by these planets they frustrate the partner and they have a hard time with. The Moon with Saturn makes a person very sensitive and emotional in nature. Saturn has two friends, Mercury and Venus. Saturn aspected by these two planets gets help in relationships and the relationship will be more enjoyable and fun loving.