First -- NO SIGN is all roses and clover. Your grasp of Saggitarius in its fullness needs to grow. Sagittarius, a Fire sign, is concerned with individuality. Sagittarius tends to become engrossed in the self above all else. It can bring self-satisfaction, or complacency. The sign can be oblivious to anything outside its own private reality.
Jupiter is the planet of opportunity, and Sagittarius is oportunistic, to the point that people and relationships with them are based on the cooperation they provide the native in the satisfaction of his aims, and last so long as the cooperation endures. Sagittarius is dispassionate. A law unto himself. Nothing is but you, all else exists only as it relates to you.
It would be easy to write a couple of pages about Sagttarius. Perhaps further study is a good place to start.
Because you have 5 of the 10 planets in Sagittarius, a powerful aglommeration of energies all in one sign called a Stellium. Pluto, Sun, Mercury, Jupiter and Mars all inhabit this Mutable Fire sign, which is also the sign on the Ascendant.
Jupiter is in his own sign and his own natural house. He is lord of the powerful stellium, in the 12th House; he is also accidental lord of that house because Sagittarius is on its cusp. Not only that, but he is final dispostor (lord) of every one of the ten planets (follow the chain of disposition). On top of that he is Lord of the Horoscope (the planet ruling the sign on the Ascendant.) His aspects are a sextile to Moon in Aquarius, nearing the cusp of the 3rd, and square to Saturn in Pisces in the 3rd. Jupiter receives Saturn. He is also conjunct Mars and Mercury. With the power of Jupiter in this chart no restrictive orb need be applied, especially within his own sign and house. Jupiter and Mars straddle the Ascendant (powerful element in the personality, self-projection.) Mars is accidentally more dignified because closer to the Asc and applying to it by direction; but the exceptional power bequeathed to Jupiter in this chart increases his influence. This conjunction across the Ascendant thus becomes a primary factor in the life.
Hmmm. So we can begin with a study of Sagittarius. All signs, all planets have both a positive/constructive side and a negative/destructive one. And then we must turn our energies toward an equally deep study of the potentialities of Jupiter. Jupiter, called the Greater Benefic, very often brings great harm. We must first understand both the positive and negative manifestations of Jupiter (as well as its deeper meanings, function, purpose) and then decide whether it will tend more toward one extreme of expression or the other, based on its conditioning as described in the preceding paragraph.
The shaping or form of the chart exhibits a planetary pattern in which all of the planets are contained within less than a trine span of the zodiac, what is called a Bundle pattern. It shows someone who is "all bundled up within themselves." It shows a private world -- here we see the theme we found in Sagittarius repeated in a slightly different way. This pattern has a hard time getting a perspective on the world other than from a very exclusively personal perspective. There are no oppositions that might allow a broader view. This is a self-contained personality -- again repeating what we saw in the very powerful Sagittarius stellium. Hmm, the plot thickens. This planetary pattern goes on to tell us much more.
At the cutting edge of this bundle stands Pluto. The planet occupying this position always, without regard to other factors in the chart, exerts a pervasive and powerful influence on all affairs of the life, on all aspects of personality. Therefore, Pluto also comes to the fore in this chart. Pluto is one of the most complex, mysterious and powerful of the planets. These planets, all of them, represent primal forces, psychological energies, powerful urges that must be and will be fulfilled. Here, Pluto is conjunct Sun and Mercury, and Mercury is Cazimi. Suffice it to say that whatever Pluto touches is hugely intensified, is a law unto himself, is isolated and walks his own path, is an outsider or outcast.....and lots of other neat stuff. So study Pluto.
And don't forget to study the 12th House. It's where the action is. And of course, don't you just know it, the Twelfth House is almost universally the least understood, most difficult to understand of all the houses. Among other things it contains isolation, self-defeating actions, sorrow, self-sacrfice, and holds the personal unconscious. It's a dark house of mysteries. It is a house of moksha (a Hindu term, worth investigating). So if, as you say, Sagittarius is jovial and buoyant, then joviality and buoyancy are in jail, for the 12th House is jails and bondage.
There is more to understanding a horoscope than just saying "My sun is in Sagittarius, and I'm One Happy Guy."
