Hello Chawalji.....

yes as a rule it is opposite to rahu..........

There is a saying in sanskrit ....kujathva ketvaha & rahu & saturn  always rahu follows saturn & ketu follows marsa.

Though mercury & mars exchanged there houses..being ketu in lagna with mercury in aries & rahu in tula....Imprisonment 100 % .
Aries means in his own  lagna in Rasi with Mercury Ketu is well placed in mesha ...hence he has very good
security against all odds & also his intelligence sources is good enough.....But being Rahu In tula 7th house...polygamy a known fact got 3 wives & He will be Imprisoned after a devastating war ..eight house chandra -sani yoga ..moon debilitated..& saturn in 8th will  much worries.........Because mercury in lagna  soft spoken .....& Religious.....because of exchange
of houses of mercury & mars .......He is causing terrorist activities....period he is running is very
bad....Though Russians wanted him 10 years back
..because of Ketu in strong position in aries...Rahu in  tula & saturn  eight house ....

Best Regards
Srinagesh