Let’s look at important things here –
Mercury - Mercury represents communication skills, marketing, calculative ability, younger siblings, hobbies, skills with hands, intelligence, quick decision making, logical thinking, youthfulness etc.
Ashlesha - Ashlesha represents our insecurities and weaknesses as a human being. It is a nakshatra of clinging on to someone or something. It also represents psychological issues. For more information on Ashlesha Nakshatra, please check this link - https://www.astrosaxena.com/Ashlnaksh.
Cancer - As Ashlesha is a part of Cancer, Cancer sign and its representations become important. Cancer is 4th sign of Zodiac Belt, hence it represents the things represented by 4th house like Mother, Mother's Care, Emotions, Taking Care of Others and Nourishment etc. Cancer is consisted of 2 and half Nakshatras namely Punarvasu, Pushyami and Ashlesha. Cancer's lord is Moon, which again represents almost same things which Cancer and 4th house represents.
Moon - As Moon rules Cancer, Moon's position and dignity is important to know about the overall functioning of any planet in Ashlesha/Cancer.
Mercury - As Ashlesha is ruled by Mercury, Mercury's position and dignity will also have an important role in functioning and results of any planet in Ashlesha.
Houses Involved – Also, we can’t afford to forget the houses involved as a planet can be ruling different houses and sitting in different house for every person as per ascendant and planet’s position. To know overall affect, we have to consider the houses involved as those areas of life are being impacted.
Interpretation of Mercury in Ashlesha Nakshatra – Here, Mercury is in an enemy sign of Moon and in own nakshatra. Although, Mercury is in own nakshatra but Ashlesha is one nakshatra which carries a negative rapport and it continues even if its own lord Mercury is sitting there. Ashlesha basically shows our insecure human nature which likes to cling on to others and Mercury represents our intelligence and decision making skills. So, when Mercury is in Ashlesha, person's decision making skills get seriously impacted due to his own insecurities or fears. He takes decisions based on fears and insecurities rather than logic and rationale. Mercury being in enemy sign Cancer of emotions also doesn't help the person a lot and person may end up in deciding things emotionally. This trait can even go to a deeper or more serious level if Mercury is in Gandanta degrees of Ashlesha. If Mercury is a relationship oriented planet for a person then similar insecurities and clinging approach would be seen in relationships. Positively, after going through all these emotional issues, it can eventually make someone a good counselor to guide others in right direction. If person is spiritually evolved then he can utilize the same Ashlesha energy in Kundlini Activation.
Role of Moon – Moon's placement is important to guide Mercury in right direction, being Cancer's lord.
Role of Mercury - As we are trying to interpret Mercury only, we need not to see Mercury's placement separately.
Other Factors – And of course, we need to consider conjunction, aspects, house lordship, house position and dashas etc to know the exact results of Mercury in Ashlesha. So, we always need to take a holistic view of chart rather than just 1 planetary position.
Conclusion – So, this is how I see Mercury in Ashlesha can work in a chart.
Hope this helps. Please post any comment or query you may have.