You have to read some books on astrology.
Retrograde means backward moving.
Rahu and kethu move always backwards.
There is nothing extra ordinary.
Prosperity of rahu dasa will depend on how the
owner of house where Rahu is located.
Suppose Rahu is in Mesha,if Kuja is placed in
kendra from Lagna,Rahu dasa will be very good.
If Rahu is seen by a good planet,then Rahu dasa
will be good.
If you are suffering in Rahu dasa,you have to do penance
for one year to improve life. email@example.com